I thinking about converting my ’75 164 Automatic over to manual while I've got it torn down for a repaint/re-buid. Being an automatic it currently has a 3.31 rear end ratio. The M410 overdrive transmission models had 3.73 rear ends. Would the 3.31 be too tall for the M410’s .797 overdrive and 3.54 first gear?
Later model 240s had 3.31 rear drives with the M-46’s 0.79 OD to improve gas mileage, however, the 240 is a little lighter and they lowered the first gear on the M46 to 4.03 to help it off the line.
Has anyone else done the swap on a 164 keeping the 3.31 rear end? How does it perform?

Thanks,
Preston