I think the airplane at the Crawford Museum in Cleveland is a Wedell-Williams, although it has been 20 years since I have been there.
The San Diego Aerospace Museum is building a GeeBee from scratch, if anybody would have references, they would! Also the curator is a modeler!
You can make some assumptions if you can't find good photos, though. It's a welded steel tube airplane covered with fabric, so the tubing will be visible and probably painted gloss black. The tubes are welded up in a bridge truss, go to Aviat Aircraft and check out the Pitts S2B parts catalogue http://aviataircraft.com/cat_Model.asp
The fuselage is rounded out using wood stringers, so they will be between the tubing and the fabric, placed at the ridges in the fuselage fabric. Throttle, mixture and carb heat will be on the left side tubing, and control rods will run from there to the engine and most likely will be bare metal. Other than stick and rudder pedals and a seat belt, there isn't much else. I don't believe the R1 had a shoulder harness.
You could probably come close to the actual interior without any references at all!