I should close the loop on this question. In the end I decided to get a Robbins top from British Parts Northwest. It is exquisitely made. Like all tops that I've put on, they optimistically put only enough snaps in the kit to do the job, none extra in case you screw one up. And I screwed one up, so off I went to my wife's favorite craft store to get some more.
The Robbins top is cut to exactly the right size, so when I got it tensioned properly around the header bar, there wasn't any extra cloth that needed to be trimmed away... none. That is a marked difference from my Midget top, which included an extra 3" of cloth at the header bar. That top had been made by Kee, and when I trimmed away the extra, I was amazed that it was so precisely 3", as if they'd designed it to be that way.
I also got a new header seal from VB, along with lots of other little hardware bits. My old header seal had collapsed years ago, so a previous owner glued a rubber door seal to that, which also collapsed. That new header seal really takes some force to clamp down!
Also, the little steel channels for the header seal that need to be pop-riveted to the header bar require an extension on the post of the pop-rivet to allow the pop-rivet to reach the bottom before pulling the bead through. I found some nifty polished aluminum cylindrical beads at the craft shop that fit around the pop-rivet post to allow me to reach that 1/8" down into the channel. Craft stores are pretty handy, and I think I was the only guy in there.
Scott