See original page number 1772b (file page n39) of the magazine "Aviation Week" in the link below. They refer to fitting a Stromberg NA-R3 carburetor (same as the data plate on your carb) to an airplane engine being developed by a company in Lansing, MI.
The manifold "hot spot" seems to agree with the Model A dimension (slightly higher than the centerline of the exhaust ports) but I'm not sure a Model A exhaust manifold would be the manifold of choice for a Pietenpol.
The intake manifold may sit "closer" and fastened "to" the hot engine block than Model A design.
Copper IS a possibility, as is the Marvel Mystery Oil shroud.
The Stromberg-Bendix NR-A series of carburetors was common in the early years of aviation. The NA-R3 would have been one of the smallest of the type produced that still had a manual mixture control. Engines like the Continental A40 and A50 might have used it. The Lycoming O-145 and Franklin 4AC 150 are other candidates. The Continental A65 engines had a 4-bolt carb flange.
Marvel-Schebler pretty much took over the small aviation carb business in the modern era.
The oiling modifications by Bernard Pietenpol were extensive to get full pressure to the mains. The original oil return from the side was deleted so all it needed was a plain cover plate. That one was likely milled out of aluminum plate. The magneto installation was another big mod but I don't know if the mag he used is all that common. TCM-Bendix or Slick type mags are about all that is available now days.