I've been collecting Iver Johnson guns for over twenty years and to the best of my knowledge the Super Trap was only offered in one configuration. I have numerous original catalogs and have never seen anything regarding special orders for the Super Trap.
They took special orders on the Skeeters, the Hercules and Champion models but these seemed to be relegated to chokes, barrel length, recoil pads, auto ejectors and grade of wood
The only shot gun I've ever seen with an English stock is the 410 Hercules or the Skeeter.
If someone has more info I would appreciate hearing from you.
I am a AH Fox collector and have little experience with Iver Johnson double guns. I found this Iver Johnson Super Trap ad and it only specified a full pistol grip stock. This gun has a long tang trigger guard that may be original?
The gun also has a single trigger, but the ad does say that a Miller single trigger was available.