Not the model you want, but to give an idea of similar sight set-ups, there was an old version of the default BSA model, the Meteor, which had the rearsight assembly fitted to the rear of the action dovetail.
The open notch rearsight was replaced with an aperture blade assembly. Known as the Meteor Cadet it was marketed at small cadet units who lacked rimfire range facilities.
Attached FileThe BSA Meteor is very much a basic entry level type of airgun.
With regard to the Weihrauch models, I'd also suggest the HW99s as a very good design...as is the HW77K, which is an underlever type.
For rear sight apertures, a few of the US makers produce models that fit in a standard scope dovetail - you'd just have to make sure the one you choose lines up with the front sight blade
In the US, the firm Pyramid Air seems to have a good reputation