Ok, so, i've gotta get around to assembling one of my transmissions soon, and trying to decide which to use, i've got two, one from a corvette MM6, the other a GTO box with the MN12 gearing, tire size will be a 255/40-17 ultimately for daily use rear, as for the rear gear ratios, i've currently got the early Q45 center section in, with its 3.54 gearing, but of course it would be pretty easy to grab a J30 R&P and install in another Q45 housing, giving me the 3.91 J30 ratio, and I have also been looking to pickup a newer Q45 3.69 center also.

Gearing for the MM6 box:

1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th .74
6th .50

The MN12

1st 2.97
2nd 2.07
3rd 1.43
4th 1.00
5th .84
6th .56

Here is a dyno graph of a LS2 GTO with the same cam i'll be running, which should help a little, this should be about the same as what i'll put down. The blue lines