Not sure of HP?

With a stock cam and heads hp will be close to stock. Those are two areas that ford is extremely conservative with. The gains from your mods won't be fully realized intill your planned mods are in place.

Oh, and 76 had the pistons down in the hole for reduced compression. Smaller chambers or thinner head gaskets will help. When you get the heads off, put it on the timing mark and measure how far down the no1 piston is. Add that to your head gasket thickness. You are shooting for about .039. Look up the # on the top of the piston and the head casting # and figure cr. A radical cam and low compression won't pull a string out of a cat's ---. CR and valve timing MUST be inline to make good power.

The 76 motors had the Grand Canyon sized dishes in the pistons, if your block has these, coupled with the 78-85 heads, your compression ratio will be PERFECT for supercharging with the ratio down around 7-8 to 1. I also agree with Brian's statement about the rest of your "mods" , they won't make a hill of beans worth of difference with an engine as de-tuned as yours. Best thing to do is open the motor up and see what pistons you have, coupled with what heads are topping it, before spending any more $$ on "mods" I'd estimate the HP at the flywheel at best 175 hp and this is if the comp ratio is 8 to 1. I know hearing this is disheartening, but you asked an honest question, and I don't sugar coat things here , sorry