I think it depends on what is available for your differential, I would be
looking at either 3.73, or if they make a 4.10, as I am looking at fitting a
T56 with racing 374 cuin Nascar engine, 4.10 ratio 7000rpms = 180mph approx, this
this will give a good acceleration, but my T56 will have a 0.75 sixth gear,
this also gives about 2350rpm at 60mph or about 3000rpm at 80mph.
You may want to use a 3.73 ratio and my car is on 25.6" diameter rubber,
and that will give you approx 2150rpm at 60mph. Best thing to do is
use a calculator, here is web link to a good graph type gear ratio!
I personally think having a 0.62, 0.50 sixth gear as ridiculous unless you
have a big block which only revs to about 5500rpm or less!
http://www.geocities.com/z_design_st...ion_z28_6.html