727 poly engine transmission

.............The 66 727 will bolt up to the 273, but the converter snout is too big for the 64-66 273 crank flange register, so its a no go unless a 67 crank is swapped in........ur 273 would have a 904 behind it........the 66 727 has a very low stall converter...I replace the front input shaft for a 67-70 input shaft, that way u can use any 67-86 non lock up converter in it, or ofcource u could swap in the lock up parts and use a lu verter....kim.......