With regard to a topic that is in the solutions to questions section about Detachable Hard Top interchangability this is a quote from a Mazda technical service bulletin on the subject…
“The Detchable Hard Top (DHT) supplied for the MX-5 NA model can be fitted to the MX-5 NB if the following modifiications are made.
1. The wiring harness fitted to the heated rear screen element must be removed from the NA DHT and an NB harness installed…
2. The right and left-hand door weatherstrips fitted to the NA DHT must be removed and the weatherstrips from the NB DHT installed. This will allow the windows to seal properly against the DHT, preventing wind noise and water leaks into the vehicle.
THe necessary parts are available as a kit, part number MCAF 850. Refer to the Workshop Manual part number 1608 10 98A, pages S-5 to S-9 for instructions on replacing the door weatherstrips and adjusting the doors and windows to ensure that they seal correctly.”
To be honest I’d be supprised if that kit is still available and as mentioned, people fit NA DHT’s to NB’s without changing the seals and without experiencing any problems.
There is some more light reading on Miata.net