Shooting 35mm on a RB67. Hi, 
I've been shooting on my RB67 for a bit now, and id like to try shooting some of my 35mm film on it. I understand that I need to unload it in the dark and such, but I was wondering what back would work the best on it? I have the 120 back, but wouldn't mind splurging ~$40 for the 220 back if it makes it easier. Thanks!