Normally the pressure plate is different due to the different thickness of the film and due to the fact that 120 has a paper backing and 220 does not have a paper backing, 120 will have a tendancy to jam in a 220 back.

I have found a cheap source of 220 on ebay, I purchase quite a bit of 220 film on ebay for really good prices and have never had a problem with any of it.

Good shooting.

Dave Parker
Ground Glass Specialties
Satin Snow(TM) Ground Glass