Here's my best guesses --

Scroll mold was made by Burt Co., though I do not know origin date.
In fact, it is STILL available for purchase, in regular and oversize chip sizes, through Classic Poker Chips. (The company in Maine, run by Spragg & Sarles, etc.)

Here's their mold listing page --
http://www.classicpokerchips.com/pokerchips/realclay/molddesigns.htm

In those days, Burt Co. had the mold and made the chips for mold owners. Some molds were exclusive to one company, while other molds were considered "open molds" and available to multiple distributors who were the middle-men between Burt Co. and the customer (the casino). That may have been the case with the SCROLL mold, so that various companies ordered them through the years.

There's a history page on the Classic Poker Chips website that gives some other interesting info.

Also, FYI, the Sillcocks name is the printing company that was contracted to produce the litho inlays seen on the center-inlay chips.

Hope that helps ... and that my guesses are correct.