With your combo, I would say that you are good to go with the 8 3/4 like Wild Bill said suggesting to have the housing braced and to remove the posi for a spool. My 1970 Dart with a small block Koffel's Place motor, 904 transmission with a Griner transbrake, 8 3/4 braced rear end with the smaller 742 housing, stock caps, 4.88 gears, spool, 33x16x15 slicks. I have made a best pass of a 9.78 @ 140mph! My 60' times are consistently 1.28 - 1.29 leaving @ 3,000 rpm's! With me in the car and 100 lbs. of ballast, I went over the digital scales at 2,795 lbs.!