John:
I used a 3:08 rear in my second 428cj ERA427SC with what ws then called a Doug Nash 4+1 (now Richmond) where 5th is 1:1. I thought that combination was great. Numerically, 4th gear (1.24 ratio) worked out to be approximately equivilent to a Top Loader four speed with 3:54 rear (See:
http://www.richmondgear.com/07pdfs/RG23.pdf)
If I ever build another big block car with that rear gear ratio, I would use the Richmond 5 speed (where 5th is 1:1)
Jim