I got lucky and picked up a mint Linhof Master Technika. Because of work, I won't be able to actually get to using the camera for a week or so. I'd like to start off shooting Polaroids with it so I need to know what kind of Polaroid back that I need. Just a regular 4x5 back or some other kind? I think I saw a few 545is on eBay, do they work? Thanks in advance.