Ohm br-30

We have a pair of original ohm br-30s and have unfortunately blown one of the original fostex drivers and after alot of searching we have come to realised we cannot get a recone as they are the best part of 25 year old so would anybody have any ideas what drivers would be a good replacement the chassis for the drivers are an odd size and modern driver do not seem to fit and we do not want to start cutting into the cabs to alter the port to fit newer drivers I have attached an image of the original so that you can see what I mean

I would start by measuring from one screw hole to the one straight across it to get what size they are. You can still see that those are Fostex Proffesional Series. Here is the info I was able to find on the internet about them...and it is not much. This at another forum.
forum.speakerplans.com/ohm-br15s_topic87984.html