Unfortunatly what your missing in the equation is that these motors don't make any power or torque at 7800 rpm's the torque falls off way below 7000 and the max hp is in the 6500-6800 range, so running a motor up that high will actually make you go slower. Thus the 4.5 ratio.

D Series Transmissions only need a few things to work well for a long time (assuming a street car rebuild) a) new syncro's, and bearing set, b) a Quaiffe or compatable diff., c) 4.5 4.7 ring & pinion, d) mobil 1 redcap (50wt) motor oil changed after every 3rd race.

Get the right parts for the right year gearbox and forget all the chatter about trick this or that, micro-polishing anything, and carbon fiber performance parts. Just get quaility oem compatable parts assemble it correctly and maintenance it.