Turbo 350 slow into reverse

[natedogg]

I had the THM 350C in my 85 C10 rebuilt recently by a local because of a delay of about 10 seconds when shifting into reverse. After the rebuild the delay is about 8 seconds now. Hot or cold it does this. A premium kit was used with all seals and clutches. A TRANS GO shift kit was installed before the rebuild. Other than this delay, the trans works great. The guy who rebuilt it doesn’t know what the issue is. Any idea what the problem is? Thanks for all replies.