The first thing I would do is pull a head off to check what kind of pistons I have flattop or domed. If it has flattop pistons the compression ratio will be around 8.2 with the 781 heads. It would probably be better to find a set of closed chamber heads to use with flattop pistons. Casting numbers 3964290. This would boost the compression up to about 9.1. A good hyd. flat tappet cam to use would be Howards, Hydraulic Flat Tappet Cam & Lifter Kit, Chev BB - Competition Products
. Don't forget to get valve springs to match camshaft. An Edelbrock Performer RPM dual plane intake and a Holley or Quick Fuel 850 carburetor will add the finishing touch. If I were you I would sell that Torker intake and Edelbrock 750 carburetor. That torker is worthless as a stock intake.