Did you consider it a worthwhile exercise?
I did at the time but must have lost interest otherwise I wouldn't have sold it. But I've always liked the 2x1 format.
Here's a few pictures with as much as I can remember.
I removed the whole front section with the lens and shutter. As I planned to use a lens mounted in a shutter I didn't need any of it.
I also removed the hotshoes and blanked the holes but you could leave them in place as an accessory shoe.
I flattened the moulding on the front to give me a flat surface to work with, cut out a hole and mounted a M42 lens flange which I must have got from a camera I guess.
I used a macro adapter with M42 threads front and back. I must have done some tests on the lens first to determine the back focus distance before selecting the macro adapter. That might also have been part of the reason for flattening the front of the camera - maybe the lens mount needed to go back a bit.
Then I got a metal M42 body cap to use a a lens board and cut a hole in it to mount the lens
I did some focus tests and marked the macro adapter with some distance points.
That's about as much as I remember.