The 727 transmission is a heavy duty unit (emphasis on "HEAVY") that is at home behind a 440 wedge or 426 Hemi. It has the capability of handling 600-700 HP without a lot of failures, but behind a slant 6, it's just excess baggage, in my opinion. The unnecessary rotating weight that must be spun up, will slow a slant 6 car down at LEAST .15-sec in the quarter mile, maybe more, compared with a 904... which can be built to handle 600+hp...
I can't see why anyone would want to use one behind a slant 6. Even the turbo motors (and my own supercharged 360 Magnum) work well with a 904. I think they put them (727's) in slant 6 trucks and taxicabs.
If performance with a slant 6 is your goal, the 727 is not the way to go; too much parasitic drag.
