Need help with 383 setup
I think that you may want to recheck your weights on the engine. As mopar says that they are 135lbs. heavier and when scaleing them, BBD to a SBD they are close. Also a 727 to a 904 is a difference of 35 lbs. and the same as a powerglide 100lbs w/o the converter. Also theres only a 5 HP difference in the two trannys for drag so with this the 3 spd. will be faster. More gears the faster the vehicle, for instance top fuel locks the clutch up 18 times in the 1/4 and pro stock shifts 5 times, so if they are the same weight then the 3 speed will be faster with less gears.
BJR Racing