[Leica] Even larger format questions

[photo.forrest at earthlink.net (Philip Forrest)]

Firstly, I'm looking for a retaining ring for a Graflex 90mm WA Optar f/6.8.
Looks to be a Gr4aphex No. 1 shutter, but right now won't securely stay in a
lens board.  This, of course, is for the next generation of my
homebrewed-hacked-up panoramic camera, which brings me to the second part of
my post.  

I'm wanting to use a Voigtlander Avus 9mm x 12mm for a higher quality
version of my 6x12 panoramic.  It has 18mm of rise (when camera is oriented
with the long axis vertical), up to 15mm shift and 9mm drop.  The quality of
this all metal folder is so much greater than the Kodak folders.  The front
standard of this camera is top shelf and the movements are finely controlled
with gear drives, not as sloppy as the wandering ones on the Kodaks.  Yes, I
could use a Crown Graphic, but here I'm just wanting to have a smaller, more
portable camera (one fourth as large as the Graphic as a matter of fact)
with some front standard movements to use with rollfilm.  Does anyone have
any experience with these?  Voigtlander offered a rollfilm back for all
their sizes of the Avus but they look to be made of unobtanium.  Here I'm
faced with the engineering difficulty of mounting a 6x12 rollfilm back
(either homemade or from a factory) while still desiring to keep the camera
as original as possible with use of the ground-glass.  So I guess the
question is: has anyone undertaken a similar venture?

Thanks always for the immense amount of knowledge here.

Philip