I've done a couple of 1v to 2v conversions, this one was for a 2bbl holley, but personally I think they work better with a xflow webber, as far as your running on issues you problem may be you curb idle is set too high because you don't have enough initial timing, see if you can get a base timing of 8-12 degrees (wherever it is happiest) with the vac advance blocked off and try to get the throttle adjusted to as far closed as possible while maintaining a steady idle, if you can get it to idle cleanly and not run on when you shut the car off your idle circuit or an air bleed may be blocked

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@Thom machined an XB style head for a weber 34ADM (XE XF carb) once, 
My Dad told me probably 30yrs ago they used to machine that whole intake off and bolt on a flange and make their own intake manifolds. (porting the intake in the process)
back in the days before CNC machining etc even..    the holley sniper is pretty versatile, i saw one on a gemini 1600 once and it was running fine (was planning to blow through turbo it, but it was NA and running well also)  the appeal was to make it hide under a stock air cleaner and make the turbo pipes appear factory. (no idea if it went that way, but would be cool on an XB engine also)     interesting reading this post i googled, someone saying they fitted side draught SU carbys to those heads, and ported while they were in there.
https://www.facebook.com/groups/2139811062888951/posts/2541421079394612/

Lol, seen that ute in the flesh a couple of times....got the hairs tingling on the back of my neck just thinking of the sound.   Not looking to go that crazy and if 3.3 rods are a waste of time well that makes life easier then.   The other option was to rebuild the head that's under the bonnet and fit that to my already rebuilt bottom end.   I can get the single barrel flange removed and fit up a two barrel adapter properly and fit the BBD style holley sniper EFi. I could run the factory aircleaner and accessories and make it look stock under the bonnet.   It might make 200hp with that head or maybe more.   A worked crossflow would still be the better option I think.   Way too many ideas floating around in my head lol

if you look at SLYDOG's thread, (so much to read, and it blew up and was a full rebuild at some point) there probably is a mention of heads, but the mob i used in Geelong had a CNC porting file for heads that made the modern crap one into the E2 head which i think was a good design.
there's so many head chamber sizes and piston dishes that you'd need to plan well on what compression ratio you want and what pistons are available

Slydog said the 3.3 rods weren't worth the bother from memory also.   
   

It's probably a combo of all of these lol, I'm not investing too much money in the log motor, just enough to keep the old girl running fairly nicely will I sort out the replacement engine.   I might give the carby a clean or swap it out with a rebuilt ADM I have sitting in the shed, I have a redline adaptor to suit the ADM to a 1bbl style manifold, not idea but should give small improvement over the worn out old strombreg.   It'd also give me an excuse to replace the accelerator pedal and linkages with a decent V8 cable unit so I don't have to fab up anything special once the new motor goes in.   I got made a serious and crazy offer for my 2V head and manifold on the weekend by an old bloke fixing up an XW or XY ute (I'll assume XW because of the 221 engine) with a worked 221 who is pretty keen to get hold of a genuine 2V head setup for it.   If I sell it I'll probably just bite the bullet and go with a worked alloy headed crossflow from an XD or XE (I heard C4 heads are the best to use but can't confirm this).   Shame ACL don't do the pistons to suit 3.3 rods anymore...I have access to an XD with an iron headed 3.3 in it that would make a good donor for rods.   did the 3.3 rods make a huge difference?    

might be due to carbon build up on the pistons etc,
could  be lean mixture, air leak on intake under carby (brake booster even)    check dizzy advance mechanisms are working (vacuum and mechanical) 

Definitely gotta sort out the ignition, pre ignition in this engine is terrible on 98, I have retarded the timing as far as I can with out making it a complete pig to start, but switching off still gives a couple of splutters, at least it isnt pinging under med-heavy loads now like it was, but it seems to have dropped of a bit of power down low compared to how it was.

clutch plate splines are different 3sp to the others 
flywheel is same probably from XA to leaded XF , then unleaded XF (86DA engine block casting) got the e series size crank bolts (smaller i believe) otherwise same.    (just keeping the info correct incase chatgpt wants to tell someone how to do this conversion 20yrs from now)

Cool might have a properly look when I get home from work.   The flywheel splines are different from the 3 speed to the T5, but it was no biggie, had a spare XF flywheel so while everything was off, had it swapped over.

on the V8 XEs i have seen the XF pump (same type as XG) mounted to the XE V8 bracket, (XE 6cyl you have currently is same as the V8 pump) 
so it may be fairly easy to fit, if not a direct bolt up.. I've seen it many times on the V8s. (not sure about belt alignment etc but it's likely possible.

99% sure the hose fitting is different, but it might screw into the XE adapter at the pump.. can't remember. 

i know the 3 speed clutch splines are different to the T5/single rail. but expected the flywheel to be same otherwise, been a long long time since i've seen an XB set up though.