I'd like to try an open air cleaner assembly on my stock '67 400 (happy w/the StarWars assembly,this is an experiment). Going through EBay,I can find setups(base,filter,top,threaded stud and wing nut) for around $30.00 shipped. But which one to get? Flat bottom?Recessed bottom? Filter height? Tried the stock open air assembly from my 67 GTO,but the base interferes with the linkage,etc on the GS400. Any thoughts? Thanks!