Unless you have the 727, I would go 904, it would need a different driveshaft than the 727, but I would not put a 727 behind a small block. I just changed from a 727 to a 904 and all said and done will have picked up 2.5 to 3 tenths. Now, I increased my flash rpm by 300, in the same dia converter. Both were PTC 9.5” converters. I also changed to the low gear set inside the 904. I also went aluminum for the driveshaft. So it is not just your typical 727 to 904 swap, but no more 727’s for me. Just not necessary. As an added benefit a much lower risk of shattering the drum.
This isn't the race forum and no asked about picking up a tenth.
True, but he’s running headers so he probably isn’t a restoration/date code/part number guy. If he has nothing on hand there is no reason to run a 727, except if he cares that it might have come with one originally. Racing or not, do you want to run a less efficient transmission? More power to the wheels, better mileage, safer, comparable cost. Valuable info no matter what you are doing with the car.
