I would venture that 200bhp on Aldons rollers with a 40 'lader is not realistic.
My Full blend, 1473cc, BVH etc motor (with custom PSD map) only made 167bhp, albeit freshly built. I'd expect to go above 170 now it's loosened up a bit but finding an extra 30 is highly unlikely.
Only thing I can think is an even smaller pulley (I know Steve had a tiny one on his tin can at one point pre turbo) but even then 200 seems a bit far fetched and you'd be rebuilding the damn thing every few weeks!
My expectations of 200bhp at the last RR day were off the back of the "190bhp" Jabba demo but the number being lower than you were led to believe in no ways slows down your progress I can assure you!
170 real G40 powered bhp with a nice flat torque curve in a G40 shell is shitloads - well, plenty anyway IMO.
If you really want the magic number, as others have suggested the only really practical way of doing so is to go turbo, and from the testimonies of those who have gone down that route it is a very well rounded and decent setup to boot.