Jim,
I've seen a few posts mention a Porashce 3.28 R&P. To my knowlege, the 951 (944 Turbo) used a 3.375 R&P, and I have seen no reference to anything of a lower numrical ratio than that; again, to my knowlege.
You might try the local POCA, or more specifically, the 951 racers. They often...