The 48-97 (marked EE1) bases interchange as do the butterflies
Choke plates interchange as do the tops, keep in mind the 81-97 have a provision for a choke lever plunger, the 48 top does not.
Choke lever/kicker interchange from 81-97
Throttle shafts interchange, though the 81-97 throttle cams have two settings- Summer/Winter
Accelerator pump levers and linkage interchanges from 48/81/97
Accelerator pumps interchange 48-97
Fulcrum screws interchange
And hand throttle lever interchanges.
Jets and power valves interchange, although each model has a specific size for stock applications!
I probably missed something.
I've rebuilt one or two that had a 48/97 base, a 97 throttle cam, and a 48 choke lever and top. Probably a lot of Frankensteins around.