64 mercury comet engine swap ideas?

I have a 64 merc comet 2 door fastback 289 c4, engine ran ok but the carb was plugged up pretty bad so a bit hard to tell engine health. I just finally got around to running a compression test. Cyl2 was 30 and cyl4 was 60. I put a bit of oil down cyl2 and it jumped to 60 so it’s safe to assume bad rings. On a 60 year old engine that’s never been rebuilt there’s no surprises here. I plan on putting some stp in the oil and running it for a bit but eventually swap to a newer 5.0 from the late 80s early 90s mustang or truck. Mainly because I can find a decent one from a yard slap a bigger roller cam in it and run it for fairly cheap. Main issue is that I have the 5 bolt tranny bell housing so I will need. To swap my bell housing to 6 bolt and input shaft if I’m not mistaken. Does anyone know what parts I need to pull this off?