[tc1cat]

Tapered pin and seat sound good but would not be my choice for a PRV. I deal with tapers every day at my real job. We make our tapers down to .000015" tolerance on diameter and .000015" tolerance on taper. These tight tolerances are used for a pressure fit of the male and female tapers. The parts are not held together by any bolt or screw just the mating of the 2 tapers under any type of pressure. A PRV using a tapered pin may lock up on you if the 2 surfaces were close to a perfect match on tapers. It takes a lot of force to get 2 matching tapers apart. Some times they don't have to be that actual close to make a very secure fit. This is in the medical field for replacement hips, shoulders, and knees.

I would use a ball bearing rather than make a tapered pin.

Just my thoughts and opinion.