This should be easy. You need a quick release Arca compatible plate:
View attachment 260643
this one has a 3/8 thread that I guess can be screewed in the Norma circular base plate, but check the threads in each side.
Also take a well reinforced enough one... Some DSLR+Zoom weight more than the Norma, so quality plates made for Pro DSLRs jobs may work, still overload well it at home to test it, you may mount the rail alone and pressing in the tip of the rail to see if the plate is strong enough. I I'd buy two to break one in a test.
Perhaps it can be interesting you get a long one to provide a good base for the Norma's clamp.