.
I think 5K is reasonable for that. It looks to have been well done prior to the accidents so it was probably sorted out and ran good. If I had a GTX that I was rebuilding to near-stock (not restored), I'd happily pay that for it.

On the other hand, I have seen some mighty impressive work come from Russia, Lithuania and Finland. Apparently, they are fearless over there when it comes to rebuilding totaled wrecks.