Linhof Tech III Mods

I have a 1942, or so, vintage Tech III mod 1. Works great but unfortunately, the back takes only Linhof 13x18, single-sheet filmholders. 13x18 is expensive & I could only find 5 of the filmholders, so I'm thinking of converting it to 5x7. I have a B&J 5x7 back w/groundglass & if I can figure out how to remove the rotating back from the Linhof, I'll drill & tap the back & screw the B&J back on. Having said that, does that sound reasonable? Are there any things I'm missing? This isn't a rangefinder, so I don't have to worry about cams & such, but it almost seems too easy. Thanks for any input or advice.

The Technika III was introduced in 1946 so you have a Technika Medezin

Thanks, Bob. Any idea how I get the rotating part of the back off?