what i'd do is grab the $150 one below and slap it in pesonally, gets it going easy. fix the original later maybe.
351 into XF, bit of mucking around but i've done it in a weekend when i had all the bits ready. 
the heater pipes foul on the engine/heads so there's a couple of ways to get around that.    the gearbox crossmember on XF only has one position unlike XD/XE,  you might need to mod the cross member to suit depending on gearbox choice (a 351 and FMX auto from 1977LTD dropped straight into My brothers with the heater pipes bent up (they cracked the solder, so this needs doing with heater core removed) and some hammering of the firewall.    used XE V8 accel cable on the thermoquad carby, but if you have a holley you can use the 6cyl cable from the back side instead of pulling from the front.     

Also how hard is it to pull the cam outta one of these. If that's my issue I could get a used cam pretty easy.

There's one near me for $150 but at the same time there's also a 351c for sale near me for $800 so you can see my dilemma. The only reason I wanted to keep the Crossy is because I thought this car was a survivor. However with the rust and dodgy repairs on it the rose tint is starting to wear off. Honestly it all depends how much is required to put a clevo in it. If it's not gonna take forever then I'll probably do that (I got the legal side covered allready so it's just mechanical). However if it isn't gonna take too much to fix the Crossy then I'll keep it as I do like to keep things original. What are your thoughts?

i reckon the pushrod falling out would have been from a sticking valve or lazy lifter (sitting ages issue)   that "lethargic" Intake Cylinder 1 valve, if it is moving less (appears so) if you were comfortable undoing the rocker, pulling the push rod and then finding a way to pull that lifter out (i find a sharpened bit of coat hanger wire can hook them out, might need to lift them up and down several/20+ times to get the carbon off them) you can see if the lifter is wiped out (if so, the cam will be wiped out)    if it's not causing issues (other than running a bit crap) i'd just drive it and see how much you like the car etc. 
i had a crossflow with a wiped cam, chewing lifters once, it would wear down one lifter and get all clacky and i'd pull the worn out lifter and fit another second hand one in, get another 10,000km out of it and repeat. (find another engine in the meantime)    if you end up fixing everything that's worn, you'll be clocking up a decent chunk of money (price a cam, lifters, timing chain for eg i doubt you'd be under $500) and then you still have a worn out rings/bearings engine and a full reco would be up around $4000 by the time you did hoses, belts and coolant/oil/ plugs/cap/leads and all the rest.   fair chance someone with a crossflow fitting a V8 will give a good running one up for $250 odd if you keep your eyes peeled 

I noticed that the cylinder 1 intake valve looked lethargic so I recorded it. What do you guys think?

Still runs like crap but the knocking is gone. Still popping tho so I'll check the valves. I took this video of it for your viewing pleasure. Let me know if you see something off

@SPArKy_Dave What's the torque spec for the rocker arm bolt?

Something seems off

Look for loose rockers   If ur keen to go further, unbolt/remove the intake rockers, then (firmly) tap each valve stem with a nylon/soft blow hammer. (using a normal steel hammer will damage/mushroom the valve stem tip)   Tap hard enough, to slightly compress the spring/bounce the valve off it's seat and back. Listen to the note.   You'll hear any stuck valves.

I'll pull the cover tomorrow. What specifically should I look for?