gears and converter for an L78 cammed big block

[GreenLS6]

I Extensively test and dyno with the LS6/L78 cam.. with the Oval port heads and Manifolds in a 454 with 10.1 comp and a decent intake. you should have 525ish ft. lbs. of torque. DO NOT ADVANCE that cam in a 454 or it WILL NOT pull past 5000 rpm.
If your repro cam has the 114 lobe separation RETARD 2* ..with the oval ports it will loose No torque but will pull to 6200rpm.. minimal loss to vacuum.
Don't be afraid of the exhaust manifolds - I have made way more power than you think in my Pure Stock motors and pull to 7k + in my L89/396 ... 6800 rpm in my LS6 making North of 550hp with UNPORTED HEADS AND MANIFOLDS.

consider a Yank 11" convertor , they work nicely.