Nah, you can add a 4v intake manifold and a 4 barrel carb to 351 2v heads, but you aren't gaining much. Check out putting some aftermarket aluminum heads such as AFR's then add the 4v intake such as a Weiand Stealth and a 750 cfm Holley with some decent long tube headers and an X pipe with your twin 2 1/2" pipes and flowmaster 40 series, then you will have a seat grabbing setup with those 3.55 gears, but you will get a bigger punch with 3.73's up to the 4.10's. Now, that all is based on the fact that you also rebuilt the bottom end of the engine with correct pistons, rods and crank. However, this will drastically change the look of your original engine. If you want to keep it original looking when you pop the hood, then follow Jim and Stephen's advice. Power costs a lot of money. And, no.....hotrodding is not out of vogue...just enough money to geter dun..... I guess what I am saying, is that there are a lot of companies who make basic rebuild kits for all engines, but if you want it to be more than the basic 351 engine at say 277 hp that you already have, you need to be inventive and get outside the box to think about your engine rebuild.