TH350 Tranny is it going to be a problem when?????

[1979blkchevy]

Hello everyone just wanted your advice or your 2 cents about th350 trannies!! What i was wondering was how much of horse power can you put to them intil something happens to them? The story is I just ordered a 383stroker with 460hp and 480tq to implant in my truck so right now im doing my cooling system over and ect to make sure this motor runs strong and stays cool and ect!! so i got thinking about the tranny if i was going to have to switch to a th400 or a 700??

thanks in advance guys