Correct intake manifold gaskets

[az1970k5]

Did a search but couldn't find any useful information regarding this. I have an edelbrock performer intake on a 350 with a quadrajet. I didn't have any leak issues but I decided to freshen things up a bit. Now I am wanting to put the correct intake manifold gaskets. My manifold and engine have the intake crossover passages. The PO had these open. I noticed some mechanics recommend these be open and some recommend them to be blocked off. My question is which way is the best and what mainifold gaskets are recommended? I live in AZ so getting to operating temperatures is not a big deal as it is 110 in the summer and no more than 45 degrees in the winter.