Hello kristiani, Welcome to the forum. I suppose the question I would ask is, are you going to drive the bike on the road or are you going to track it (or both)? If its going to be a purely road bike then I would probably keep it standard enough MC18 spec. Will the few extra horsepower really mean that much to you on the road by putting so much money into it? maybe it will. However, maybe some tyga pipes and an airbox mod would be a nice subtle upgrade and easily reversible to 100% standard.

Although the only issue I would have with the standard approach would be the MC18 crank, as Andy said. It is tough to get them and sometimes they cannot be rebuilt.

The SP engine would be nice in it as cranks are readily available, but expensive. But its just not the same imo as having the original engine for the bike, and Andy has a great idea in swapping the dry clutch over.