A wordpress/etc plugins make sense to me - create 'blog' profile, store keys in the plugin, export all content to long-form (existing & new as published), notify in admin area about kind-1 comments etc.

Flood isn't a problem, at least for now - the load will be trivial, and you could set created_at timestamp as old as you like (to match the dates on old posts). The issue is that most relays won't accept old events atm, so this would require some (paid?) arrangements with relays.