I run the M1 on a flat hood Challenger and 400 block. It all fits (just) with a mild drop base air cleaner (Edelbrock) and short EFI throttle body. With a R/T hood I guess it would fit with a taller carb and similar drop base air cleaner.

FWIW I kinda like the M1 single plane on my stroker. It runs well and also tested well in the Hot Rod BB manifold comparison. The engine has more than enough low/mid range torque and hangs in very well if I spin it up.