1970 OMC Engine ID help amp Vortec Upgrade

"Hello, I'm just starting

"Hello, I'm just starting to rehab an older Penn Yan boat with an OMC motor. I'm certain it is a SB Chevy-based motor, but I'd like to know the exact engine block type and displacement for upgrading to a vortec top end. The information I can uncover is that its a 1970 boat and the motor is original, so I'm sure its a 1970 motor. It is an OMC part number TFJ1-10B and is listed as 210 horsepower. Can anyone give me some more insight into this motor? Ideally I'd like to find a donor motor with a vortec top end that I could use to convert this to fuel injected and give it some more oomph.

Thanks!
-Adam"

"It's probably a 307 Chevr

"It's probably a 307 Chevrolet.
Your OMC drive system coupler will only mate with pre-1987 SBC engines with the 2 pc. rear main seal design, or the new Mexican sourced crate engines using that design.
I'd forget Vortec, and just get a new 350 GM Crate engine. The 290HP crate (It makes 260HP in a boat with a quadrajet.) sold by GM today uses the old crankshaft design for the OMC coupler.
Your outdrive is only rated to 260HP anyways, and you don't need injection for that.

You could do the swap to a crate 350 in a weekend and for half the cost of a coast guard approved fuel injection system."