Hi!
I don't have this particular Pitts, but I have flown several bipes of this size.
A 10cc (.61) engine (two-stroke) with a 12x6 or 13x4-5 APC is going to fly this bird just fine.
Under 3kg ready to fly seems very low and if this is true you are going to have a very aerobatic airplane indeed-
Regards!
Jan K
Sweden