OMC went out of business many decades ago.
I can't find in any forum where another crazy person did something similar.
Plenty of people doing boat restorations.
most people avoid anything OMC
to properly convert an old OMC powered hull to outboards and get the boat in good condition will most likely cost you more than 5-10x what you could ever get for the boat when it comes time to sell. most people that have attempted outboard swaps on here usually abandon the project.
stringer, transom, deck repair alone on the boat will cost you $
the engine is just a small block chevrolet truck block and heads. so you can get parts for the base motor.
but the shift cable is bad and the exhaust manifolds are toast
depending on how bad the exhaust is, it may have taken out the motor. the motor itself if in good shape is worth more as a cleaned up longblock than it is as an OMC upfit motor. as a cleaned up longblock, it may be worth $250 as an omc motor with toasted manifolds. maybe a $100
exhaust manifolds are only available aftermarket.
the shift cable is $800-$1200 alone.
have you checked the ball gears? vertical 3-piece drive shaft?
both will need to be replaced. that is about 1600 in parts, not including seals, water pump, etc.
there are companies out there that specialize in the stringers.
If it was me, I wouldnt have bought anything OMC. they were obsolete back in 1985 (actually a left-over 1984 because the Cobra came out in 1985)
to part out or restore is totally up to you. if you absolutely love the boat. I would suggest removing everything OMC. redo the transom and get a Mercruiser or Volvo Penta longtail to replace it.