I'm confused about the drop question. I know of two 32" barrel Sterlingworths that had 2-7/8" and 3" of drop. I also owned at least one Sterlingworth 16 and one Sterlingworth 12 with 28" barrels and 3 inches of drop.
The 12 gauge was probably minted as a Fox "Field Gun" as opposed to a "standard" Fox. It had slightly more open choke borings (.015 and .032).
Also, the production "Brush Gun" came with cylinder and Mod borings. I've only handled one of these while I have handled 26" guns with Mod and full chokes. My two 26" guns did have 3" of drop...that's why I sold them...
Bottom line is there is a lot of variation in the many Sterlingworths available out there. The buyer should be aware and careful to get exactly what he wants.