If I got a micrometer how would I check the lift on the cam? 

Ok I'll give it a go. Also how do you get it out past the head

they won't be mushroomed, it will be carbon build up on them. 
just work them up and down as much force upwards as you can each time, they'll come out.  if you can rotate the engine a little to put that lifter at the lowest position first, it will get sort of a run up in a yank to pull it out, i don't think you'll get much spray down the side of it, it will just need working up and down.     

Well I went at it some more today and checked the valves. I hit it with a dead blow and it was perfectly free, however the lifters are a different story. I worked them up and down but couldn't get them out my guess is mushroomed faces on them. After throwing the valvetrain back together it ran the same and the vac gauge still showed a missing cylinder. I noticed some glitter in the oil sitting in the rockers while it was running so that doesn't seem good. I reved it and managed to get the cylinder to even out at about 3000 (you can see it in the vac gauge) but it was hit and miss. I noticed that it was easier to hook into the lifter on the intake valve with there seeming to be more space for the tool I made to go in so it might just be a sticky lifter. Any advice on how to get the lifters out?

I can imagine... When my XF was running poorly, I drove it up the street to test, and it barely got out of it's own way.   I'd suggest to get it running nicely first, then decide. It's a big expensive undertaking to swap in other drivelines and have it daily-driver reliable. (especially these days, with rising costs, etc)   It should be brisk and torquey, but not certainly 'fast' like a modern vehicle. World's cheaper/easier to diagnose/maintain and repair though, and I'd choose that any day.  

From ur video angle, it looks like no.1, no.4 and no.5 intake valves aren't opening correctly. Either partly bent pushrod/s (remove to check) collapsed/stuck lifter, or worn camshaft.   I'd also see what the vacuum gauge reads, now that loose pushrod is fixed.   If u have a lifter removal tool, with some maneuvering, u can remove the lifters without undoing the cylinder head. Same for the camshaft. The radiator/AC condenser needs removing to get the camshaft out though.   With my XF wagon, I removed each lifter and disassembled/cleaned/refitted them. I had x3 bent pushrods, all on the intake side.          

Around 20-25nm I believe

I can't remember what gearbox you have?  if it's auto, then there's column shift V8 stuff that would fit up to it the same.    if it's manual, well you'll be unlikely to get it working (not sure i've seen a falcon with 3 speed V8 manual)
 

Yeah mines much slower than that. I forgot to mention that the bolt was backed out and someone else had been in there as evidenced by all the bolts being finger tight and the rear one being gone so I'm wondering if someone's been at it before

i had seen some XFs with the 2 different crossmember spots, likely the leaded ones but not idea to be honest.    the lifters when NEW have a dome shape on the bit that runs on the cam ( i have never seen this on any used ones) when they are normal they'll be fairly flat(they wear in on cam run in). when they are stuffed they are dished inwards, and when the cam is wiped they might not even have an even base but they'll not be looking good. (pull the one out next to it that is working better, and compare.. )    google has some pics on this link    
this was My stock standard XF ute column auto one, ZL fairlane cluster fitted.  probably on LPG.