Clois-
I wouldn't recommend using any gasket.
1) Put the side gaskets on then lower the manifold onto the block. See how much of a gap there is between the manifold and the block front and rear. This will let you know how much RTV you will need to put on the block so it will seal.
2) Clean all surfaces thoroughly.
3) Scratch up the front and rear surfaces with some 80 grit paper - do the block and the head.
4) Smear a thin coating of RTV on the intake and block surfaces - let it dry.
5) Build up a layer of RTV on the block that is higher than the gap you found in step 1.
6) Lower the intake into place - a second (trusted to follow directions) pair of hands is helpful.
7) Torque to spec.
I have never had a leak doing this. I have had leaks w/using gaskets.
Using an old ditributor as a locating guide for the manifold also helps - just cut the top off. It also makes a good "bushing" for priming for
oil pressure.
Pat