First off, if you are talking about the GM 4.3, remember, it is esentially a small-block with the front 2 cylinders loped off. The pistons, con-rod, bearings, rings, are all the same as the era 350..identical part numbers is bought individually. The vavletrain is the same as well. And, most, if not all 4.3s came with a roller cam. The rollers, for soemone who is familiar with working vavletrains, yes, they are a "drop in". The hardest part for most people is settign the lash without collapsing the lifters, BUT, if you get a Haynes, or other manual that covers a vehicle with that motor, you will be covered. And holley upgrade? which part are you talking about. I know I may have missed something. And yes, we always use RTV between the manifold and block in the front rear...

My 2 cents

Chase