Why not, that's what most of us do anyway...alternatively drop DSN an email, he should be able to help. Also, our resident watchmakers on this forum should have a spare or two, if you ask them nicely
if you are in canada, you could go somewhere like RPM Canadian Bearings, they have thousands of gaskets in all sizes. I remember going there for one wierd one for my land rover, and they had exactly what I want. these ones are pretty simple and straight forward. In the states, just look them up in the phonebook.