Thanks for the suggestions, everybody! I developed my first roll of Tri-X from this badboy today and they look great, although several shots are blurry as I'm not used to such a heavy beast after being accustomed to my super light Rolleicord. :laugh: I'm going to go to the optometrist store/place tomorrow and inquire about a corrective lens and then I'll also see if I can give Koh's Camera a call sometime. I'll let everyone know if I manage to get a corrective lens.
Sometimes a diopter from another manufacturer can be adapted. In this case I got a Contax branded negative diopter lens that matches my perscription for a few dollars on e-bay. I attached it to the back of a Rollieflex with some silicone glue. It could be removed if I so desired.
In another case I found that the Nikon round diopters screw right into the back of the BESSA R camera viewfinder (note: the Nikon diopters are purposely marked 'wrong', see Nikon website for details).