4 to 5 speed upgrade

[McSparky]

I have an 85 FXST W/4 speed electric+kicker.
I also have a trans from an 85 FL (non softail).
Will the 5 speed gearset work in the 4 speed case?
I see many 85 to 89 FXST compatible cases advertised.
Will the FL gears fit?
Is there a compatibility list available?

Thanks,
McSparky