Marking the List B species as unavailable (I understood that it is planned to proceed so) bears a general potential problem.
The List B species are currently considered as available names. Their taxonomic status is currently unclear (this could change with any neotype designation), but they have been made available in a correct form. So List A names that are currently considered as primary homonyms of List B names (and for which substitute names may have been established and used) will (after approval of the LAN) be released from their senior primary homonymies and suddenly become admissible for usage. This may provide instability and threaten the current usage of names.
I would not remove the status "available" from the List B names. If names were not used after 1899 they can be suppressed under Art. 23.9.2.
(Maybe this comment was posted doubly...)