I have a GP Ryan at 11 pounds with a Laser 120, APC 15x6 at 8.8k which is a bit more powerful than my OS 91 4s with APC 14x8 at 8.4k. The PT-19 is very similiar but lighter and would fly fine using the OS 91 4s. Flying the Ryan I can do big loops, 75 foot vertical wing overs and large cuban eights with the Laser. Note that you have a long nose moment on the PT-19 and a heavy motor will need lead in the tail. A Saito 100 would be the lightest of the motors I would use if I had one. My OS 108, APC 16x6 at 9k is considerably more powerful than either of the 4 stokes mentioned. I use 5% fuel in everything. I just hate seeing an engine poking through the cowl anywhere.

It should be a very nice plane.

Carl