Regarding the George Carlin: It would be funnier if my answer was: Well I have two mommies. I was about to say I have two dads (it would be funnier than two mommies) but then again I would not exist otherwise.
No I believe it's fine to do both, it will definitely be a beast. But my inderstanding is that you can correct the speedo with a tune, and since you'll be getting a tune with the supercharger you could do it all at once. But you could just do the gears and deal with the speedo until you do the SC. I will ask someone more knowledgeable than me about the other stuff.