the lists in SCSW 4th ed show K307XXX as being shipped in 1957, just about the time the Model 17 designation was added. Is the revolver in question so marked?
“The gun is in very good condition” is really not specific enough not determine a price, but generally speaking all of the K22 series seem to be pretty strong in holding or increasing their value. Has the seller suggested any kind of price he wants to get for it? I’m guessing without box and docs, it will go for anywhere from a bargain price of $500 or less to an asking price of twice that. But without more information, I’m just guessing, and that’s worth exactly what you paid me for it.
Froggie