First it needs a good cleaning with some metal polish. Never Dull might do it on that gun. The grips are not factory, they Pachymahr presentation grips.

It is a fairly late made gun probably late 70's to very early 80's. The 6" barrel is less desirable than the 5" or 6.5". If the gun cleans up well I would expect it to go in the $750 neighborhood depending on your locale maybe more.