I've got a couple of B30E's here but I don't know if the balancers are in usable condition or not, probably not.
My father has a 1947 Daimler, among other cars, and he's reconditioned balancers for it and others the same, by machining out the old rubber and machining the surfaces so that new rubber can grip the metal parts well, he then mounts the two pieces in a jig and takes it to a place in Melbourne that vulcanises new rubber into them.
They are a much bigger design than a B30 one, but it may be possible to do something similar.
I also have this among my parts for sale:
