Hi Mattias,
I’ve ordered Elastic Rubber Edge For the 8” basses.
Why don't you use foam surrounds as Philips did back than? These 8 inch surrounds are readily available, even surrounds for Albeka 8.5 inch are available.
Information on Olle Mirsch's högtalare (love this swedish word that means speaker) is quite rare, but there is some information on
https://www.faktiskt.io where Olle has been active during his late years (he died some years ago) and there's also a facebook group 'Olle Mirsch Högtalare'.
My Mirsch (two sets now) still need new surrounds fitted to the bass drivers... but I already have
custom made badges for them
bis denn,
Christian