[Formerly Steve Wilkinson]

I'm assuming first that you understand that neither your heel nor your toe actually figure in heel-and-toeing. It's the left side of your sole (on the brake) and the right side of your sole (on the throttle). You _roll_ your foot to give more gas while you're braking. I've never understood the purpose of those replacement pedal sets that provide a gas-pedal extension for your heel.

That said, your 911 should be one of the easiest cars on earth to heel-and-toe. With the throttle pedal in the proper position--and maybe it needs adjustment, which can easily be done--it should be pretty much at the same "elevation" as the brake pedal when
the brake pedal is depressed to a point where it is applying moderate braking pressure. Maybe you need to lengthen the rod--which has threaded ball-end adjustments--between the back of the pedal and the bellcrank behind the floorboard.

Stephan