I don't think that's a Grade II Sidelock, Adam. I'd guess a custom restock. Gerry's may be, although I've never heard the game scene sidelocks referred to as Grade II's.
John, I collected a bunch of information on Ithaca SKB's for a couple articles I did for Shooting Sportsman 10 years ago. Spoke to an Ithaca salesman who sold 900 of them (both OU and sxs), just in MO and KS, in a single year. The 60,000 figure came from a couple different sources. But given 900 in 2 states in a single year, I see no reason to question it. And they're certainly not rare guns on the used market. How often do they show up compared to NID's--and 45,000 of the latter were made? The SKB sxs sold well enough that Ithaca continued to expand its offerings as time went on. They first appeared in the Ithaca catalog in 1967, but the 280 was not added to the line until 71.
Counting all gauges, I'm quite sure Galazan is well over 1,000 RBL's.