Nitro Star T-15 engine is pretty damn reliable(If treated right). I have one in my MT2 used it over 15-20 tanks, its still on its 1st glow plug, and it started everytime within 1 second with a roto start (I converted it back to pullstart seeing the rotos a pain in the ass) . Its also a damn low priced engine usually $65 USD on ebay.

The RS4 Evo 3's base is solid seeing its essentially a MT2 with shorter arms, shock towers, and a handful of different parts. At least he has the aluminum steering knuckles, I know the stock plastic ones suck ass from experience on my MT2