Yeah, it was freaky I tell you--for a few minutes I felt like I was in a Hitchcock movie. Maybe this is how birds pay their respects?
And yes, Meat Popsicle, this was one of the Rutland "Grapho-Glas" kits that comes with 7' of flat gasket "rope" and a tube of high temp cement. (The part # was 95-6 if anyone cares). I suspect I would have to shim the back edge of the grill at least 1/8" or maybe as much as 1/4" to get an effective seal if I used the Rutland gasket there, and the 7 feet included in the kit left me a bit shy of the length of material I would have needed anyway. Instead I may try a traditional oven/range door seal, which has more give/loft to it. I haven't had any luck finding the thicker fiberglass rope that you used.
I had been thinking about sealing this grill up for a while, but I never really got too confident with any of the design ideas floating around in my head. Instead I just used aluminum foil (the "duct tape of the BBQ world") as a band-aid for a long time. This thread turned out to be just the kick in the ass I needed to try to set things up a little better.
If I had to do it all again I would have spent more time working on the fit and finish, but I was more concerned with seeing if this setup would even work, first. Some more work with a metal file and a rattle can of high temp black paint should cover up the ugly bits well enough. And with nearly 2 years of continuous exposure to the elements, the whole grill could use a restoration about now anyway.