no the motors are the same its the stroke thats different i did it with my 79 malibu 305 with 350 heads and a edelbrock carb and intake blocks are the same thats why the heads bolt right up its not gonna be a ten second car but trust me you will feel the difference

 

Yea some 350 heads will work with the 305, some probably wont, it depends. Is it TPI or TBI? If TPI, get some used 350 heads, port n polish intake and runners get some headers and a cat-back, it should make some power. Maybe a cam, roller rockers, etc, but then your talkin more money and taking most of the motor apart. If it's TBI, I'd say get a GM performance Vortec manifold or an Edelbrock performer TBI manifold. Then a bigger throttle body or a TBI spacer (but then hood clearence might be an issue.) Get some better flowing heads, 350 heads or some aftermarket 305 heads. And do an exhaust (headers, cat-back)

 

Ido not know what your budget is........definitely do not put 350 heads on it,that will only drop your compression, I'd look into a NOS sniper kit,..... That will wake her up, world products makes pretty sweet 305 heads, but still you are limited by flow, throw some 373's in the back, that'll help..... brother there is really only one choice if you are going to do all that.....355, or 383. hope I helped.