I think HR-03 rev.A [not plus] could fit on 8800gt

[Vapor]

I have the Gigabyte 8800GT and the diagonal distance between the 2 mounting holes is indeed 75.2

My only concern is whether the smaller contact surface of the HR-03 Rev A. is sufficient to cover the entire GPU.

Before the HR-03+ came out, people were jerryrigging standard HR-03's onto G80s and they worked decently well (much better than stock, but high loads didnt do so well). G92 is much smaller, so it should work