Your Nova has only one set of crossmember holes, but from what I've heard, the Turbo-400 crossmember is the one to use. It places the mount a few inches to the rear, and about 1/2" to the right. You may have to redrill or slot the holes to get it back to the center. You can get one at an early Camaro restoration supply place, and it bolts to the same place your current one does. Aftermarket suppliers (Bow Tie Overdrives, etc.) make crossmembers especially designed for the swap, also.
I'd try it with the 3.08's before swapping gears. My T-bird ('88, 302) came with AOD and 2.73's, and it would run 75mph all day without dropping out of OD except on a serious hill, but by that time I would have shifted it out manually anyway. It'd probably have been just as happy with 3.08's.
Last edited by jimfulco; 10-02-2006 at 10:41 PM.