I believe Derek with the brown 240z with a Buick engine had or still has one. LT1 with a turbo. There were pics floating about it here many many years ago.
not exactly a G body.
I have a 96 LT1 in my 71 el camino,
direct from the corvette that crashed (not me)
using OEM computer ( reworked) with 4L60E,
nothing special, just smooth reliable quiet efficient.
OH, and 25 MPG hiway!