Graflex RH-50 back modification to 56x112mm (61x125mm?)

Has anyone modified a Graflex RH-50 70mm film back from 56x72mm to a panorama format? Does it hold the film flat without the thin metal pressure rollers on the inside of the backplate? Do you just file the window to 112mm or even, as I seem to recall reading somewhere, to 125mm? Is it possible to also widen the height, to use the maximum usable area of perforated 70mm film?

I've been trying to contact Andy Buck, who posted about such a modification on Photo.net, but mails keep bouncing back. Does anyone here knows Andy? Help is much appreciated. Thanks.

Would be interesting to hear whatever you find out on that. Finding a good cheap 6x12 back is challenging. The horseman is superb but pricey.

Apparently, the pressure plate (later, flat version) is the key, not the thin metal rollers. Those can be successfully repositioned to the very edge, i.e. near the rubber/plastic rollers. Filling the holes in the plate seems to help with film flatness as well. I'm still waiting for the detailed explanation and pictures from Colin Turner in the UK, who's had a RH-50 modified and had used it with IR 70mm film.

EDIT:
Andy Buck's reply:
"It's been many years since I did that. I sold the back several years ago after Kodak radically increased the minimum order of 70 mm film. My memory of the back modification is that I just eliminated the two rollers. The opening was widened just to the top of the rollers, making an opening about 124mm wide. I simply wound it twice. That lost a little film but I wasn't concerned about. I did not increase the height at all. Good luck. It was fun while it lasted…
Andy"