Well, that would only work right if he wanted to dispatch of the gearbox as well as the hoffco clutch is for the CVT transmission.
I'm assuming by centrifugal clutch you want to make a semi-auto quad so they still have to shift, just not learn how to take off with a hand clutch.
The semi-auto gear boxes actually use two clutches... one is similar to the one under the side cover of the blaster only it's exclusively actuated by the shift lever (instead of the left handle bar). The other is a true centrifugal clutch call the "primary". The "primary's" center hub turns all the time and outer bell is only turned when the engine is turning fast enough.
The outer bell of the "primary" is geared to the outer hub of the "secondary". The "secondary" is engaged all of the time except when you are shifting the bike. When you are shifting, it breaks the torque to the transmission input shaft (inner clutch hub) to allow the transmission to shift under no load.
There is no room to put the primary clutch under the side cover as it sits. I'm not saying that it's impossible to put a centrifugal clutch on a blaster. With a milling machine, a lathe, a bunch of billet aluminum, a donor clutch and an engineering degree anything's possible!
You best bet, if you'd like to retain the shifting a general "sporty" feel of the blaster (with a huge sacrifice in actual sportiness) is look for a honda 250ex. They're "sport" 4 wheelers with semi-auto transmissions.
If sporty isn't such a requirement, you could look for a beartracker, recon, or quadrunner. They are all 250cc with semi-auto transmissions.