You can go both ways on this one. On one hand you can never have too much power, it gets you out of trouble many times. So you could put the .76 in a .40 trainer, add some weight aft, with will be necessary because the plane is not designed for that much weight up front, and have the ability to save it by flying away from difficult situations, something you whouldn't be able to do with a smaller engine. Also, when you get used to it, you will still be able to have fun with it and not put it away right away.

On the other hand, a .60 trainer is bigger, it flies better, it handles wind better, you can see it better and further away, it will fly slower because it will not be overweight, and so it will take off and, most importantly, land much slower.

It's up to you. My opinion is go with the .60 size trainer. It's advantages are more important for a begginer. It is very frustrating crashing your trainer before you learn how to fly well enough to be ready for your next plane. Trust me, I know. But that's just me.

Hope I helped