Your digging may yield more than mine, but here goes. I have 1982 Davis price list that shows a stainless Grade III build at $460. Davis would start with either a fixed sight Smith or Ruger as a basis, at the same price.
Simple enough so far, but the additional custom work to make yours into a pinto would be additional. Therein dwells the wild card. Perhaps an expensive one.
My two PPC revolvers are built up on stainless Ruger Six series. They were built up by Greg Roberts, who was in Santa Cruz CA at the time.
Not too long after I had bought my first one, I was practicing with another shooter, a top shooter who was always in the upper reaches of the Governor's 20 in CA (far, far above me). At one point his revolver, also built by Greg on a Smith model 14, jammed. My colleague opened it up and found that one of the frame mounted pivot pins had sheared off. This would necessitate a trip to Dr. Roberts. My colleague remarked that in a match he would be out of luck as this was his only PPC revolver.
My bride was there and witnessed this. On the way home she told me to order another PPC revolver to have a back up. So I had Greg build me a duplicate. For a few years this one went to the matches too, just in case. But just in case never came, so I got lazy about carrying it with me.
Just in case never did come. When LE and teaching responsibilities ran me out of time and I dropped out of competition in '84, the back up got retired too. So besides my primary I also had, and have, a brand new PPC revolver.
My extremely thoughtful and generous bride is still by my side, and still just as thoughtful and generous.