I had access to O1, used it for the body and all the parts, the jaw inserts got glass hard, the body I annealed to about RC 35. It only opens one inch. is two inches wide. I can't find a picture of it right now.
I do not have any acme taps or dies for the lead screw. I do however have some left over 5/8-10 RH acme precision rod left over from my surface grinder job. I could buy a brass insert and press it into the lead screw block. Then I could buy a few acme nuts to fit onto the screw to make my handle proper.
The other option is to just single point a 60° thread.
If the A2 has been normalized, (the way you bought it) it should be easy to work. I've not had the privilege of using it so I'm not sure. The major difference between the two is the hardening process. O1 hardens when quenched in oil. A2 hardens when removed from the heat source and waved about in the air. (air hardening) Both should be ground after tempering, (raising to about 500º F and letting cool naturally. Grinding is necessary because they swell slightly when hardened.