I built the Telemaster 40 many years ago and it does need reinforcing for the horizontal/vertical stab if you put a larger sized engine than recommended. I have an OS .55 AX 2 stroke in mine, which is great for climb performance with an APC 12x5 prop. I reinforced the tail by using an aluminum air-foiled tubing strut (K&S tubing) from the bottom of the horizontal stab to the under side of the fuse. Place the strut on the reinforced (blocked up) spar of the stab, under the fuse and up to the spar of the stab on the other side. Use Bolts through the stab and lags into the fuse. This strengthens the whole tail and the extra weight is compensated by the heavier engine up front.

Still have the plane and fly it frequently...

Have fun with one of the best flying planes ever designed!!!

Oly