Originally Posted by engineczar
To go along with what everyone is saying. Before you run the bead of RTV on the end rails, clean the end rails on both the block and the intake with brake clean. Spray some on a clean rag, wipe and then let it evaporate. This gets rid of any residual oil that may be there. RTV is great but doesn't stick well to oil.
That is correct, all the surfaces, head and end rails really need to be very clean and free of all old debris and oil. That is very important.
If you buy the correct intake gaskets matching the port size is not an issue. No need to make this very easy and common procedure any more complicted than it really is.