Close enough, if you want a bit bigger, use the props from a 1/48 Pogo on a 1/72 tiltrotor; I have seen some speculation on contra-rotor tiltrotors so there's possibilities there, too.
Figure you're going to want something in the 1000 shp for each engine. I'm also inclined to suggest a straight-thru engine rather than a reverse flow one like the PT6 as I'm given to understand that the exhaust for this engine on what's now the AW609 is somewhat problem-prone.