My main business is shortening cranks, by drilling and tapping new pedal holes. Most cranks are 6xxx series alloy, no sweat. On the rare occasion that someone wants me to shorten a 7xxx series crank I charge almost twice as much. I have to use a new tap, cheater bars on the tap handles and add extra bracing to ensure that the force needed to turn the taps doesn't move the crank in the fixture.

AFAIK I've never used 6061 rings. But I have used harder 2024 rings and they don't wear nearly as well as 7075s. For a single front ring you can't go wrong with either Salsa 7075s or Surly SS.