Actually it would be nice to have both the toploader mount and the tremec tabs already welded in.
Saves some welding on the end user, plus there isn't much to the tremec tabs anyway. I'd imagine a lot of folks don't have welders and have to take it somewhere to get it done. I'm going to ask for them installed on mine.
Doesn't appear they interfere with either setup, plus a lot of folks opt for the TKO. (I think David posted that most of the cars now get 5 speeds) $3.50/gal no doubt a consideration.
You could always put a 4 speed ball on for that "vintage" look.