v-6 in early A-body
Nv3500 is a good trans. Low first and 2nd gear to get it going. Top loader style, no rods to adjust. Make it fit and have a tough smooth shifting trans. With a 26" tire and that trans you could run a 2.76 gear easy, or 29" tire with 3.23 which is factory in my 3.9 dakota. 1900 rpm @ 70 and 20 mpg in a 4000 lb truck.