the neck will not fit over my head
Cutting a mask always makes it possible for it to tear if stretched to much, but wont affect how the mask looks or make it deformed. The zipper will have to go up the back of the head from the neck and that will be completly covered by the dreads, and if its installed right it will be very strong and durrable.Would cutting it not deform the mask? or cause the integrity(dont know if this is correct word to use but sounds good) of the mask to be weaker?
Plus velcro doesn't jam and leave you stuck in the mask for several hours.Most masks will need cutting up the back of the neck to get your head past the narrow neck area, this is normal.
velcro and zips are easy to attatch, i have used both and now prefer velcro, as it is quicker to open and the neckring helps hold the slit shut anyway.