Mrahh, go ahead and scrap the SK radar overlay idea, and just use the overlay DarkShip posted, with a tad bit more brightness. All you need to do, then is add numbers to that default overlay like follows: 5-10-15-20...and so on, like they are positioned on the SK radar screen.
In regards to your question, yes, the Radar Operator's Manual refers to both SJ and SJ-1 radar when talking about those range settings:
http://www.hnsa.org/doc/radar/part4.htm#pgSJ-2
It's down a ways on the page, under
PPI Indicator Unit.
Thanks again for your work on this!