5.9L Magnum questions

You already have tons of good advice here. I'll add my $0.02 based on my experience.

I put a 150K+ mile 5.9 in my Dart. The cylinder walls and heads looked pretty much like yours does.

- I did not touch the bearings or the rings, and I did not hone the cylinders.
- All I did to the bottom end was put in a Hughes cam that is suitable to run on the stock Magnum tune, because I used the stock Magnum EFI (cam: SER0814ALN-14). Otherwise I would have gone with something bigger.
- I bought a stock replacement oil pump. Maybe should have gotten a high volume unit, but I did it during COVID and the HV units were out of stock. My oil pressure runs at about 42 psi (hot) when running at cruising RPM (~2000 rpm). Hot idle at 600 rpm is about 15 psi. Obviously these numbers are totally fine (for me).
- I used all the factory lifters except for 1, because it had a little scar on the roller. It might have been fine, but a replacement was $10 and I didn't want to take a chance with my new cam.
- On the stock heads I spent a few hours cleaning up only the most ridiculous casting flaws in the intake and exhaust ports.
- I lapped the stock valves until they ended up with a good sealing surface. Incidentally, 5 out of my 8 cylinders have cracks between the intake and exhaust valves. Don't sweat it, the cracks don't get into water and almost never cause issues.
- I already had a set of Doug's headers on my LA 318, so obviously I reused those.
- Initially I had a 904 with a stock converter, with a 3.23 Sure Grip. The converter would flash at about 1900 rpm with the 318, but with the 5.9 it flashed at around 2100.

My engine runs incredibly well, no smoke and no blow-by, with solid compression across the board. Bottom line, considering your "20 year old's wallet", I think it's likely doing the rings and hone and block decking is not needed. You might find most machine shops won't touch the stock heads because of the cracks that are almost certainly there, so just save your money and do the best you can with them. But I think you really need to try and find a set of headers. Keep in mind headers don't only make 20+ horsepower at peak RPM, they make more power everywhere in the RPM range. And the bigger the cam the more important headers will be.

Good luck!