I spent a couple hours searching for info on the Class A's cab interior, and the closest I could find were some photos of the enclosed rear cab of a brass model. As none of the four Class A's were preserved, my only thought would be to "free-lance" the cab along the lines of a preserved 4-4-2, taking into account coal versus oil plumbing of course. There is a PRR E6 Atlantic on display at the Railroad Museum of Pennsylvania. If no diagrams, plans, or photos of an actual Class A cab interior turn up; perhaps there is a RWA member in the Strasburg, Pennsylvania area, that would volunteer to provide some photos (?). That is if you are left with no actual Class A alternatives of course. I wish I could be of more help; I really hope your Hiawatha project becomes a reality as it is such an iconic part of our railway history that cannot be properly "faked" with any of our existing models.
Viel Glück!
