So are you saying the backplate is hitting the chassis BEFORE it reaches the mounts? Like the mounts are too short?

If so I cant see how it would work and I would go with the same conclusion you already made up. The chassis is very similar to its buggy brother and i'm sure the mounts are the same - considering the fact that the Stadium RR and the Lightning 2 RTR have the same engine.

I guess if you really want more top end you can gear up - but that really depends on how much you love your low end . The Stadium's have impressive acceleration and i'm sure you could distribute that more evenly and towards the top end.

Overall if your going to look for a new engine, a buggy engine will fit. They are also obviously bump start compatible but its up to you if you want to go that route or not.