The problem is that you have a 4L60 instead of a 4L60E.
Do a search on the subject and you will find the name of the part you need (I sure don't at the moment).
Make sure the TV cable is adjusted correctly so you don't burn-up the trans

 

AFAIK, (and i've been doin this awhile) the Hypertech Power Programmer that I bought for my 1995 LT1 A LONG *** TIME AGO!, had a feature to allow 3-4 shifts at WOT.... From what I understand the tranny will not shift into OD at WOT... it's not the speed, it's that you're at 100% throttle..... if you let off the gas just a tad it will immediately shift... you might not go any faster but it'll shift..... you can buy a hypertech power programmer to turn it off i believe.....

just call hypertech and find out if their programmer can turn that off in your PCM..... although from what Ed says your PCM doesn't control your shifts so i could be totally ignorant.... i'm a 94-95 guy. dont know much about 93's and their specific "issues"

 

Forward piston? Is that the piston y'all are referring to? Not that it really matters to me I have a 96.