what transmission to use with new hemi 5.7

If your going EFi with a Hotwire harness then you might as well stuff the 545rfe in. It involves cutting the floor just the T56 you planned. However it's a 5 speed auto with 2x 2nd gears. One for cruising upto speed and one downshift gear. The 545rfe has 2 overdrives I believe as well.

The 904 and 727 are nice but having the extra gears and modern parts is a bonus.

Then again I've got a T56, so I went that route.

Riddler