AZ2000XJ

Picked up a 2000 XJ that's absolutely rust free and very clean looking in and out, shifts smooth and runs well besides some intermittent rough idle and a supposed CEL throwing a P0303 (previous owner wasn't sure, gave up on the flip and cut his losses, I have yet to get a CEL).

It's got box b mileage, carfax shows a reporting of 198k miles and then suddenly reported at 125k and now sitting at around 145k on the odo.

Fuel injectors and coil pack all look original so I'm swapping those, plus the heat shields are completely missing... which lead me to suspect maybe an engine or head swap.

Also interesting to note that the radiator and upper/lower hoses are just about brand new, still shiny and all. Almost wondering if one of the previous owners swapped the head, overheat it and swapped out cooling components and then realized they cracked their head, maybe again? and then dumped it off. But I'm also not sure I know what I'm talking about. The head bolts look original and untouched to me, so maybe this is just a really well maintained engine and the crack just happened so they sold it instead of dealing with it.

Either way, I was able to see through the oil filler that the classic 00-01 0331 cast crack in the usual spot was in fact there. Parked it, started to tear the engine bay down and got the valve cover off and here's what I found:

https://imgur.com/a/msBNcoM

Clearly there's a crack seeping coolant and it almost seems too dry nearby like there should be some oil? Maybe plugged rods? Doesn't appear to be any lifter bleed; I cannot manually move any of the rocker arms. Also appears some rocker arms aren't getting as much oil, is that normal? There's just a bit of carbon and milky residue around cyl 3/4 and in the valve cover, but otherwise does this valve train seem almost too clean?

How does it look overall? The previous owner changed the oil and said nothing seemed off at all, no milkshake or anything. And that continues to be true, it's relatively healthy oil.

I'll be swapping the head for hopefully a TUPY recast, swapping injectors, sparks and coil pack and then installing heat shield and wrap. Anything else I should do? Maybe replace all the lifters and rods while I'm in there just in case? Or is that excessive or would that interfere with the whole "parts wear together" concept?

I've never worked on an engine this straight forward so I'm really diggin it, but I also don't really know what to look for outside of the obvious, so bear with me here. Thanks in advance!