choices...... please help

i have a 66 GTO in need of restoration, as stated in my previous posts. it's not numbers matching so im gonna customize it some. right now it has a 400 V8 out of a 1972 Grandeville. does anyone know what kind of horsepower that engine will get? the engine is in need of being rebuilt, so i'm not sure whether to rebuild it, buy a 389 4 barrel (what the car had originally), or a 389 tri power. whatever engine i get im gonna make the scoop in to functional cold air intake. the car is intended for weekend driving and maybe the occasional local show, but mainly driving. I'd like it to go fast. what would you guys reccomend.

besides cutting the hood and buying the ram air pan, is there anything else different when you make the scoop functional. is the engine any different?

you can put a good set of 400 heads from a gto and use a tripower and im sure you would have enough power to bring a smile to your face, get a set of 670 from a 67 400 or 16 from a 68 etc, put in good street cam set of factory headers or aftermarket. blocks are all the same so just rebuild what you have unless you want to go all original and number crazy

anyone else have any suggestions. please help.

If your not number crazy, get a 455 4-bolt main and use the factor stock headers and the tri-power system which alot of these engines came with out of catalinas and other Ponitacs. That should give you enough horse power and it looks great. I have a 66 GTO with a 4-speed and 12-bolt rear end with a 455 in it. I put my original engine away.