If you are going to buy an M3W and then change it sustantially with new wheels, fuel tank, modified engine, revised aerodynamics and possibly modified suspension, at what point does it cease to be an M3W?

IMHO it would probably be better to build a 3 wheeled special with that top speed in mind from day 1.

I regularly do 80mph in mine and have seen 100mph on a couple of occasions and this is fast enough for the 69 year old codger that I am, but each to their own and I hope you succeed in your quest.

I would think essential bits of kit for going that speed would be brown trousers and cycle clips.