[Arran]

As long as the center hole is small enough that you can mount the voice coil and spider to it it should work, do those have a foam or a paper hinge/surround? Or is it rubber? I too have known about the acetone trick for removing a glued on cone, actually lacquer thinner works just as well. You don't really need to let soak as long as 15 minutes, 5 to 10 is usually sufficient. You can use some strips of film negative or some other thin yet stiff plastic to shim between the voice coil and the pole piece.
Regards
Arran