The pictures are a little grainy,, but I see a fairly good looking gun. It does show some wear & such in a few places. The gun doesn't appear to be converted,, and I don't even think a "bubba" has had it apart. The screws look as if nobody has hit them with an improper screwdriver.
Since he's asking $600,, I'd be of the mind to see if he'd take $500. You can negotiate.
The RENE Guide says a mint condition (as new) where the serial number does not have a prefix,, is worth $730.00 while a prefixed one is worth $645.00.