Sadly this was one project that I didn't photograph/record so I'm relying on memory (never a good idea).
I seem to think that the glass was thinner than I expected at around 4mm. I did measure the old seal but for the life of me I can't remember what it was, however your numbers sound about right. I did measure the web, assuming this to be the critical dimension in getting it installed and then bought the nearest I could find from Seals Direct, I think it was their WR63 or 64 looking now but I can't be 100% on that.
It was a devil of a job to get it installed but I was doing it in January in a cold workshop, so that would have played a part. In the end I reduced the web thickness to get it in the corners because the bend radius was a problem - but I knew that beforehand, I do remember it was quoted at 100mm for the one I bought.
And it fits, doesn't leak, looks fine.
But I've got time to fiddle about and don't mind a challenge so if I was to offer advice it would be as the other guys have said, buy the correct seal from Lotus Supplies or wherever and rule out one potential problem area of trying to make something else fit. You will only save £15-£20 or so on the material costs, not a great amount when you look at what you're spending overall and it will save you time/trouble.
Brian