I presume you're talking about the 1/3 scale ~25 lb H9 232, for which H9 recommends a GT80. I am a fan of the Ryobi conversion, but it is an economy option, not high performance, and I doubt it would get the 232 off the ground. I expect the PT19 is the <15 lb Dynaflite, for which the Ryobi is a good match, especially as the PT19 tends to be a floater, way different from scale aerobatic. I think you're going to be disappointed with less than 60 cc in your CAP, and if you're going to buy new you might as well spend a bit more for an 80 and have all you'll need.

RCFAQ mentions a hopped-up Ryobi getting 9 lbs thrust. Standard conversion would be more like 7-8 lbs. No way that is going to fly 1/3 scale, much less hover.