The Evo 45/46 is not too much power at all. Until you get into more advanced planes, simply use a prop selection chart to match up to engines. The new engine should take a 11/6 or 7.
The cg should be about 25 to 30% of cord width back from leading edge. The 1" in front of main gear for cg is pretty close; otherwise if it was right on the gear, as soon as you hit the throttle it would drop the tail on the ground and try to lift off before it was ready to fly.
I hope this is not your first plane ??