3.23 gear heavy car with an Auto I would just as soon build with the 6.76-6.800 mainly just because my old 508 was such a HOSS and it had 6.76".
Send a PM to Paul PHJ426, I think he's running 2.94 gears and 28" tires in a 72 b body with that old 508 and he's more than keeping up with new ZL1 Camaros....with a hydraulic Flat tappet cam and ported Iron heads....just sayin.
Built a few.....not as many as some....but a lot more than most
There's a lot more critical choices to make than Rod Length if you want a combo you're going to be really happy with.