Thanks Joe. Both good ideas.
Have a couple of original air cleaners, both in good shape and hate to hack one up. I’ll keep an eye out for a trashed one with a decent base. Guess any 15″ base with no drop would do.
Great idea about the new smaller diameter base under the bigger stock top. Hadn’t thought of that. New bottoms are cheap, I”m going to give that one a try right off.