Want to Buy WTB: Prism finder for Exacta Varex IIa

A friend gave me an Exacta Varex IIa with a waist-level finder. Focus with it has been great on the screen that's in the finder, but composing vertical frames with it can be difficult.

I would love to get a prism finder for this camera to make taking those vertical shots a bit easier.

FYI: There are two versions of the VXIIa and they use different prisms. The first version used a prism similar to the VX. In 1961, the styling changed and the prism was similar to the prism used for the VXIIb or VX1000. The early version had a curved front "plate", while the 1961 used a "squarish" front plate. Both prisms will fit, but the styling of the pre 1961 won't look just right on the 1961 model, and vice versa.

The model I have has the squared front.