Right off the bat, forget about a 929 or 954 head. Barton already covered this.
Hey hey, ujm.
You may have turned me on to something.... Looks like some throttle bodies a ported stock head some valve springs and some 929 racing cams would do it.
The assumption here being that all costs are for the parts. It only begins there.
First, the 919 cam sensor rotor is mounted on the intake cam while the 929 / 954 rotor is on the exhaust cam. A small thing , but ...
Doing the porting yourself? Add the cost of a replacement head. Don't look at me in that tone of voice!
What cam timing to use? How to set it up accurately keeping in mind a range of adjustment.
Fuel management? Forget a PCIII -- the fuel maps, ignition maps, rev limiter, hell -- everything will have to be adjustable to optimize all the disparate parts into a user friendly package. Not a cheap proposition. And no, a 929 control unit wouldn't be suitable either, and would be a mother to integrate.
You're also bumping the compression, right? I mean why pack all that air and fuel into a cylinder that gives it a gentle squeeze? Tear the motor down.
And, and, and ...
You can bet your bottom dollar any 919 pumping out 160 BHP has had practically every part inside that motor inspected and tweaked in some way by a very experienced engine builder. Their time is worth every penny if you want to get out the other end of this or any performance project with your bike, bank account, and sanity intact.
Funny, I've been searching high and low for a reasonable engine kit for this thing and I think the answer has been relativly in my face the whole time if this pans out in real life. Jeez. Big thumbs up to ya!
As one who has gone down this particular garden path more often than I care to remember I can say the costs will be roughly 5 times what you think it will, at least for the first two, and the end result will be fast but not as much fun for day to day use after the first couple of months.
Turbocharging is a much better method of getting that kick in the butt while avoiding the worst of the peaky beast the 919 would have to become to get anywhere near 150 HP. Just say'in.
And then there's the chassis.