I have a similarly built 350 with crane cam, springs and lifters, double hump 2.02 fuelie heads and a 10.5:1 CR, a 600 carb on a Torker 1 intake, pushing out 350 hp and while streetable, not an every day driver. You would be better off going with a new crate motor. You can get a 350/260 hp for under $1400 and then build it to your own liking. That, plus a 12 month 12000mile warranty for putting it in a GM vehicle would seal the deal. You might qualify for longer warranty since you are replacing an original 350.

The crate engine will have 8.5 compresson out of the box and run 87 octane, mine requires premium 93/94 and at today's prices, it's not as much fun.