I lean towards Jeff's position. Let me restate it, with IIDSYCTYC in mind.

First, the stock cam timing gear is adjustable. Thus, it is legal to have an adjustable gear on that car as specifically allowed in the rules.

Second, however, comes the question of "how much adjustment is legal?" Absent any allowance in the regulations, the only approved adjustment is as specified in the workshop manual (or appropriate documents) and within the allowable range. For example, is the WS says, "0 degrees +/- 10 degrees" then you can put it anywhere within that range using any allowable W/S techniques.

After all, cam timing must be stock, correct? And that range as specified in the W/S manual is stock, yes? Thus, adjustment within that range is perfectly legal.

Even better, if allowed engine modifications do not allow you to bring the car within those specs using teh adjustable gear, I suggest that you can even add an offset key AS WELL as use the adjustable cam gear...