I've never considered if the surround kit wouldn't fit. While I've had no experience at replacing surrounds, I have fixed my share of tears in the surround and I see no reason why this won't work. I would trim the excess 3/4" from one of the ends so as to provide a "butt" joint in the surround instead of a "lap" joint. A very straight cut is important if you are to keep the circular shape intact when joining the ends. Go ahead and begin glueing the surround to the frame/cone only with the glue provided until you've gone around the whole driver. Now after the glue has set-up for a bit take a small(very small) dab of RTV Black(common auto engine gasket adhesive) on your finger and smear on the underneath side of the surround at the splice. You may have to place another finger on the top side for support while you apply adhesive underneath. You can also use some scotch tape on the top of the splice(under the finger) to help prevent the adhesive from "bleeding" through. Let set for a couple hours and install driver. Should reach full strength after 6-8hrs. The adhesive will work on both foam and rubber and provide a very flexable joint/seal although with foam, the amount of pressure should be a little greater to "embed" the adhesive into the pores of the foam. I recommend RTV because it tends to be more flexable than caulk whether in silicone or latex. In the scheme of things, the glue rigidity you are worried about probably won't mean a thing unless you get carried away with the glue but keep in mind, the more rigid the glue on "high excursion" units, the greater the risk of de-lamination or joint fatigue.

Others with more experience in surround replacement may have other ideas.