I recently got a 5.9l mag/46re cheap from a 99 durango (with all of the EFI stuff) to swap into my 72 W200.

Was hoping to do the plenum gasket, clean it up, and run it, but I don't think it'll be that easy.

Compression:
1: 120
3: 120
5: 145
7: 145

2: 120
4: 120
6: 120
8: 70

Leakdown is terrible on all of them (70psi in, 20psi out), but I think something is goofy with the gauges. The bad cylinder does have a lot of air going out the exhaust. If it wasn't for the one cylinder with low compression, I'd probably just run it as is.

What's the current status of budget replacement heads? I figure having a machine shop go through these will be at least a few hundred. If one valve is worn, the others may not be far behind? I don't think I need anything special since it will probably never go over 4k rpms. I'd like to keep them (well) under a grand.

Odessa/Clearwater has some good reviews, but might need adjustable rockers? Ebay Odessa

These look inexpensive/cheap. Ebay heads

Are either of those as simple as pulling the springs and making sure the valves aren't too tight/stuck, then re-assembling and running them?

Thanks