1.50 is too heavy for the VF 66" Extra. Adequate power would be a .91 2-stroke, like the OS91FX (some love 'em, some hate 'em) or the Magnum .91 XLS (mine has great power with Jett Engineering in-cowl muffler, shimmed head and 25-30% nitro). A little extra power for good vertical authority would be a 1.20 2-stroke (Magnum again, or GMS, and there are others).