I had a 1964 3/4 ton with the "truck" 4-speed. SM420 I guess. With a V8 in it it would run freeway speeds just fine, despite the low rear end ratio. Of course the motor was wound out pretty good. But it would go _well_ over 70. How much I don't really know; not sure how good the speedo was, but I passed people easily.
Now, with a 6 in it you might not get the high RPMs. Dunno what you can win a 250 or 292 to.
Get us some details! What engine? What rear end?
George
