What I recommend most to the fellows for the Senior Telly is any of the good 91four strokes. They are usually a perfect match for the airplane and not overpowered. Anything less even in a two stroke will be unhappy. The OS ninetyone in the pictured one has been flying about two years now and very successfully paved the way for a slow lerner to finally succeed.
For the similar type airplane the Sig Senior Kaydet ARF or Kit with or without ailerons I have found the OS LA 65 to be about the best combo possible.
I solved the power problem on my Senior Telemaster with six OS .25FX.
John
These are an acceptable engine for the airplane and pretty inexpensive, Heck they were just on sale a while back for a 150 bucks.
http://www.hobbypeople.net/gallery/210868.asp