71 Demon 340, 3 speed or 4
4 speeds in A bodies built after 1967 all had dash-mounted reverse lights.
That having been said, a 3 speed is a weak kneed wimp, if you want to thrash it at some point, the 4 speed holds up better and it's more conducive to the fun of thrashing one.
I'd go with the 4 speed.
Mark.