The lower cup is 56mm or so (without measuring it) and is onepointfive zerostack. The top of the head tube is 1-1/8" integrated.

You need to be able to heat stuff to 970F or so and quench in to room temp in under 3 mins. to heat treat 6061. I think many kilns go hotter than that.. you also need to be able to make the stuff straight and age it to full hardness at around 500F