You're also quite right about endplay. When I rebuilt my Mazda tranny, I used all new steels just 'cause they came with the master rebuild kit.
As I read through my resources, I discovered the specs & checked the numbers with old vs new steels just to see what kind of wear I had. The old steels were undersized by 3x spec. The tranny was seriously burned up. New steel brought it to the very tightest limit of spec.
