That's an heirloom quality rifle, I'm sure you're aware.
When I had talked w/ Dave, and heard his asking price, I was shocked at how low when guns that weren't custom made were listed at near twice the amount in some cases.
Yes, regulators, external adjustments, better valves have come along. Doesn't mean that rifle right there can't compete with any of them if you know the shot curve & have its favorite pellets. I believe he used LW barrels so choked & not any fussier than any other. Less so most likely. I bet he took the time to chamfer every O-ring channel he cut so reseals weren't a PITA.
I wish Dave & family all the best.