Rob,
I've never seen a sheet of decals specifically for the Hillclimb.
The JoHan Toronado Mark mentioned (kit # C-208) was nothing more than the standard Toronado kit with a set of graphics decals inspired by (but not
replicas of) Nick Sanborn's car. The decals don't even reference Sanborn, his sponsors, or the Hillclimb logo.
The closest kit/decal combination to an actual Hillclimb car was the Audi Quattro kitted by Tamiya (kit #24036). That kit replicated the scorching Group
B Audis from 1983-1987 and includes most of the graphics they displayed.
In 1983, John Buffum appeared at Pikes Peak with the first rally Quattro, a WRC Group A car. In 1984 Michelle Mouton came to Pikes Peak with a full-on Group B
Audi Quattro and posted the second-fastest time. In 1985, she returned with the car and set a new overall record in her win. The next year, Bobby Unser drove
the same Quattro and eclipsed Mouton's record. In 1987, an updated Group B Quattro came to Pikes Peak, driven by WRC Champion Walter Rohrl.
Otherwise, I know of no kits or decal sheets with PPAHCA markings.
There would be three levels of PPAHCA markings to consider:
1. PPAHCA logos. The logos changed periodically over the years as the name of the event evolved, the 'art' evolved, and when name sponsorship became involved. For example, the logo Don showed is the current, but in past years 'name' sponsorships were incorporated into the logo: Checker Auto Parts, Predator
(Carburetors), Chevrolet, Falkken Tires, etc. Thus, logo decals would be specific to a specific year to be replicated.
2. PPAHCA membership/contingency stickers. Small versions of the event logos were applied to competitors' cars to show membership in the PPAHCA organization and to qualify for special contingency monetary bonuses. The appearance and even existence of these stickers varied from year to year.
3. Pace Car / Official Car markings. These generally consisted of large PPAHCA logos for the doors of the vehicles provided for use in operating the event. We generally had some supplemental markings also; sometimes the race date, sometimes the vehicle's function (Pace Car, Safety Team, etc).
And, of course, there would be Individual competitors' cars with graphics, sponsorships, and driver's names, etc. Very much like NASCAR, the competition vehicles were/are unique to each vehicle, each year.
To create a set of replica decals will require a lot of research!