What tranny?
4.88 are real slow no matter what motor.
Poly needs more in and out, so throw a 4bbl on it, nice set of duels, it will never rev high, but it is a truck. Torgue rules.
My 134 flat head in my 48 willys with 5.38 rears does not have any top speed but pulls like hell from 400 rpm idle to 3200.
