I have one on my '28 roadster pickup with the pistol grip handle . The hole is not large enough to go over the pistol grip so I slit it far enough to slide over then put a small, black zip tie on right under the upper lip to hold it together.
A few years ago while lining up for a tour at the national meet, one guy was frantically trying to release his parking brake. I ran over to help, but I couldn't get it to release either. I then lifted the floor mat to see what the problem was, and found his repro metal plate around the added rubber boot had jammed in the ratchet mechanism. I used a screwdrive to unjam it, and he make the tour, but this is something to watch out for.
Did the Model A come with any type of boot for the emergency brake handle. I can't seem to find any in some of the catalogs ?