From what I gather the clutch used is NOT a Mazda. The Miata clutch assembly with their lightened flywheel looks nothing like the pictures JV has posted.
I think that Morgan has used the Miata trans, but has used their own flywheel and clutch setup. I think JV referenced Volvo as Morgan's possible source for the assembly he installed.
So I doubt that Miata parts are going to work. I could be wrong though...