If thats the only engine you have to work with, it should be fine. Perhaps a bit big for a 40 size trainer, but should be fine. You'll have to buy a new engine mount with extended rails for the 4 stroke. Great planes has a 40-70 adjustable engine mount that has the front wheel capabilities. There may be others as well. Also, put most of the sevos, battery receiver towards the back as it may come out a bit nose heavy. I generally dont recommend 4 stroke for training as they generally end up crashing a bit and I hate to see this investement being lost. A cheap .40 for $50 may be the better way to begin. But if you have a good Instructor, he should be able to keep the ground from sucking up your PT40.