Is the serial number on the grips the same as on the frame? Does the serial number start with an "S" or "N" again it matters. Is it equipped with a target hammer and or target trigger? Believe it or not this matters.
Best guess based on very little information would be starting at $650.00 and up. This information is based on pre-panic pricing.
I've attached two snaps of my 5" M 27-2 that was made some time between 1966 and 1967. I also have the factory grips. I value this one at a minimum of $750.00 Hope that helps.