No it's not that one. I see what you mean, one view has it supported by the trunk guide and the other by the cylinder - artistic licence I think it's known as! The other odd thing is that the area of the pump rams looks like it could well be more than that of the piston, probably OK if it were just used for low pressure pumping but would not feed a boiler.
This is the one, I was sent another image but could not work out how the thing operated. This image along with the Patent drawing makes it clearer with another chance to do a rocking valve engine. It's not big and could almost be done 1:1. Not sure if or when it may get built as the list of future projects grows at a faster rate than even I can build them
. The same source also sent me photos of an Wall open crank engine he has just got that is believed to be Elmer Wall's first engine and earliest know to exist and has a few different features to the production ones of which only a couple are know so that would make an interesting project as I have liked the look of that engine for a while.
J
PS Jo the same e-bay seller has an early Bamford Tulip engine for sale that you may want to copy the photos of for when you get round to doing yours
Oh and he also has a set of Robinson "Chippy" X-type castings for sale for those that may not have a set.