I've only seen a couple over the years, frankly I prefer the M14-6's due to the newer style rear sight assembly. Early -6's can be had with square butt grip frames if that is important to you, and of course forged parts are found on most/all the -6's as well. If you expand your search to the -6 variation you might find more out there.
Individual pics of these in this thread:
Informal Pictorial Essay - K-38 Masterpiece (and Model 14) variations