Steve Smith , Oct 10, 2007; 04:03 a.m.
I have done this exact mod to mine and it works very well. I did some research before I modified mine and other people were drilling through the top for the winder which makes no sense at all. I have a label on the bottom of mine which gives the amount of rotation needed between frames.
I used the spool holding mechanism from a defunct Agfa Isolette for the supply spool.
6 x 12 is a bit optimistic. It's closer to 6 x 10 - but still worth doing though.