700R4 advise needed

[rcbildr]

My 83 shortbed 4x4 diesel needs transmission work and I'm wondering if I could get away with just a repair or should I save up and do a full rebuild. I bought the tranny with about 2000 miles on it and supposedly it was built to the hilt...beast sun shell gear, corvette servo, shift kit, all the good stuff. When the trans was shifted in to drive there was always a little delay for it to engage but other than that the trans worked great and you can feel the shift kit....I had a tranny shop help me confirm the torque coverter was locking up too. Well that little delay for drive to engage is what bit me. I was in a rush one day and I put it in drive and gave it some serious pedal before it fully engaged and when it did it chirped the tires....I know it was a stupid thing to do.

Now the truck doesn't want to go backwards when I put it in reverse and it goes forward in neutral. I was told the forward cluthes are messed up. So should I have the trans completely rebuilt again or try to repair what's broken? It's been parked ever since because I was told that kind of damage can generate metal shavings in the tranny. How expensive is it nowadays to convert over to a 4L80E? Any help will be greatly appreciated. Thanks!!!