Can you put 2000 Chevy 350 Vortec heads on a 1995 Chevy 350 block and increase horsepower with out modifications?

http://www.customclassictrucks.com/techarticles/0405cct_vortec_cylinder_heads_small_block_chevy/index.html This will answer all your questions. Yes it can be done. There's a bit more to it than just torquing on a new set of heads, but if you can replace heads, you can more than handle the rest of it. Should flow much better than the stock TBI heads. Vortec heads flow far better!