After checking the tach had a broken signal wire. Fixed that it works correctly now.
The oil pressure gauge uses 240-33 ohm scale and the engine had a factory? GM sender that put out 0-90. Ordered the correct sender, should be here tomorrow.
The engine coolant gauge had a broken +12 IGN supply to turn it on, fixed that and it works correctly now.
Removed the crappy radio and tossed in the trash.
Replaced the Champion plugs with NGKs, installed a 750 vac secondary carb I had laying around, and fired it up. It now ran on all 8 cylinder (one is a little cold), but had a horrible vibration. Started checking and found out that 454 use external balance and 396 use internal balance. Since the engine is way older than the boat I assume someone swapped it in. Pulled the bellhousing and found a B&M flexplate with weights on it. Had to pull the engine last night to get it off.
Today I ordered paint, and Edelbrock 750 carb, new flexplate, small liquid filled coolant pressure gauge (for on the intake manifold), and some nicer hardware. Since I have the engine out I'll clean it up a bit and maybe polish the mounts.