The bracket that bolts to the trans is different than the 904 one, it has to jog up a bit before it can go down as it's slightly differently located on the bellhousing because the 727 is larger than the 904 in that area...
The z-bars are also different from 904 to 727....
Ran across that putting the son's 71 Valiant together and installed a 727 instead of 904 like it originally came with...