Kirk,
Why does your formula change the multiplier for Variable Valve Timing cars? I have seen multiple dyno sheets on Honda VTEC cars prepared to or close to IT rules and the VVT cars see no more gain than non VVT cars.
This misconception may be the root of the SCCA saddling the GSR with so much weight.
<Caveman voice on> "Oooooo... VTEC Bad" <caveman voice off>.

From what I've seen, Well built GSRs can see about 170 to 180 hp at the wheels (yes, I know all dynos and all cars are different, thats why I put a 10hp range in there. Trust me, it's close).
Well built, front running CRX Sis can see as much as 115 to 120 at the wheels.

Stock stated Si power - 110
Stock stated GSR power - 172

The VTECs gains in IT trim aren't any better than the completely VTEC-free CRX.

Fact is that the Honda VTEC powerplants are so damned good from the factory that there aren't really any big time LEGAL gains in there. Nothing in the ballpark of what I've seen on 13B rotaries.
Hell, a friend of mine took a stock 150K mile 13b last year and baselined it at 129whp. Then added an open air intake (homemade job), header and 3" exhaust with no cat along with some magic exhaust port tuning (I have no clue here, but the motor was never opened up) and the car dynoed up (same dyno, same weather) at 160whp.
You'll never see gains that easy and cheap from a VTEC Honda.

Now where's that nasty VTEC monster? Under my bed maybe?
Putting it in the same "potential gains" category as a rotary is a big mistake. But this thought process could explain alot.