The vintage trans am folks are running the 2s lipo / 21.5 combo as a legal alternative to 4 cell / stock. They call a different final drive ratio for this combo to try to equalize things. The vintage trans am folks are pretty proactive about changing the rules to level the field so it's a good place to look.
Most of the new generation brushless ESCs (Castle's Mamba Max and Sidewinders, Novak GTB and XBR, Speed Passion, Tekin RS and R1 Pro, etc) have either selectable or programmable cutoff built in (though none of the selectables I know of have a 1 cell setting).