The 3100 has pushrods which are not lined up with each other and are splayed to the side of the lifter. Hard to describe without seeing it, but they're not all lined up parallel and in the same plane as the L36 or GM 350 V8 designs.
I actually think the top of the gasket has round looped "keepers" or "guides" for the pushrods (that is integrated into the gasket)...so there may be some contact there if pieces have broken loose...IMHO possibly the source of the extra noise. Memory is kinda going fuzzy there on the details, though
A good manual would probably have a picture of the basic design of the gasket and the pushrod layout...unfortunately I don't have one.