[Arran]

Now that I think about it the basket on Philco speakers is fastened to the rear bracket with round headed pins that push out. You would still have to remove the cone but that's fairly simple, some acetone to melt the old cement around the rim, and it will come right off after a 15 minute soaking. Still, even if you don't want to tackle rebuilding the original speaker I would still keep it around in case you want to have a go at rebuilding it, or find someone else to do it, or end up selling the set later.
Regards
Arran