Restoring a very rare 1987 Hutch; trying to ID these grips in hopes of tracking down a NOS pair

After a couple years of extremely detailed restoration, I’m finally nearing the reassembly stage of my all-original, never-ridden 1987 Hutch HPV Superbike that has been with me for over 20 years.

One of the last hurdles is finding a replacement set of grips (or discovering some magical way of whitening these). No markings or IDs anywhere on them and unlike the grips used on any other Hutch BMX bikes.

Hoping someone recognizes these, so I can begin searching out a NOS set, or has a phenomenal means of de-yellowing this pair!