Even if the car is going to be restored rather than modified I'd use a 4.25 stroker crank. If the car is going to be driven at all the extra torque just makes it more fun.

A 4.25 stroke crank with Chevy 6.800 long rods and matching pistons with your desired compression ratio are just a VISA card number away. It should all drop into your existing block and use your existing parts.

If the engine was externally balanced originally and you want to keep the factory damper and flywheel then you'll have to have the new assembly balanced the same way. Or do a neutral balance and buy new damper and flywheel.

I also think you could have that crank ground down 020 or 030 and run it as is, but maybe not. Shouldn't be hard to have it checked out either way.