An LT40 might be able to handle a .60 nicely. A .46FX doesn't really have enough power for this plane, IMHOP. It flies good but vertical is seriously lacking. The weight for this engine isn't listed at tower. I used to have TT's website. Seems like the GP's don't weigh as much as their bearing cousins. He could probably get away with putting it on a .46 size trainer.