I'll have to look in Lowes, since I don't think that there are any ACEs or Do It Bests in Canada.
They do make grommets that large that you can get at ACE, at least. I used to use grommets on all of my homemades, now I use skirts. The ones that I used are 1 1/4in., but that is not the actual OD. It's the size hole that it fits into. Put a 3/4in. washer in the middle, and two 1in. washers on the outside, and really crank it down. The seal great, but not as good as a skirt.
Anyway, great writeup. It reminds me of LT.'s Reconbow, this just has a bigger plunger tube, and shoots farther.