Call Dave at Pro trans,661-940-7400, for all good race your parts and ask him on which clearances to set your front and rear drum clutch plate clearances up at and so on
I've used his race trans and parts for many years with no problems
he is the best 727,904 and Pro flyte tranny builder and Hi Po race tranny parts maker in the world
A1,A&A and a lot of the other tranny builders buy many of their race only special parts form him