The engine im building up is from a 1999 c1500. Its the vortec style heads and manifold. Now i know that if i put vortec style heads on it, then i need to use a vortec manifold (im going to be using a carb inplace of the FI). My questions is, can i use cylinder heads that are NOT the vortec style? Is the block the same design or whatever as the pre-vortec engines just with vortec heads on it?

Thanks
Nick