* i've seen this kind of Mark VI stamp before, altho I don't remember serial ranges or dates.
* might be Euro engraving, as the engraving on the bow reminds me of some Euro stuff i've seen before(off the top of my head).
* probably a good deal, but the zero feedback is of some concern.
HOWEVER, if one can strike a good enough deal, IF one can pay via ccard & paypal, could be worth pursuing.
Depending upon your location, if enough $$ can be saved, fly out there and eyeball it, or see if you can find someone in the vicinity to check it out(pay 'em a fee, etc).
I came across a mint silver Series III soprano a couple of yrs back, in the Bay Area, which is quite a ways from where I'm at. Fortunately, my sister lives out there, so I had her take a bank check and meet the seller at a FedEx office. She eyeballed the horn, read serial/stamping, etc, to me over the phone and made sure it was boxed up and shipped.
So, if you're flexible, there's probably a way to make a deal happen.
In regards to the Low A alto blurb above, yes, there's gotta be way more than 200 of these thing made.
I used to have a gold plated low A alto w/F# key. Bought it cuz I knew it was the most rare of this issue(must have cost a fortune back then, as the 'base' low A model was around $630 or so in the mid 1960's, and gold plating would really jack up the price).
Was in primo, almost mint condition, too
Sold it to a collector in Japan a year or two ago when I was cleaning out my closet.
Can't speak too much to the playing characteristics, as I only tooted on it a couple times to see if it would play(needed a pad job).
Interesting horns, tho.