i have a suncoast in my truck and it shifts pretty firm. alot firmer them my stock trans. I have been running it for about 500-600 miles without a tune and its well learned. they say about 100 miles and its good to go.
your problem could be with that banks...you have a "not stock" trans now and it doesnt know that.. i would get that sct you want and have Eric @ innovative tune it. he will firm it up for you!
now i dont know if the rebuild kit is like their "built" trans but i will say its firmer then stock and its very obvious right away.
btw why did you have it rebuilt?
edit: are you running it now with or without a tune?