Anybody here know if any of the current CZ magazines interchange with the old BRNO Model 2?

Should be no problem...better to contact Jozef (Jojo_svk) on Gunbroker and organise an early Brno magazine to keep it original.
He can access the old flat base ones occasionally as well, as well as the early Brno single shot adapter (occasionally).

His word is gold.


HERE



Flat base (early)


Single shot adapter (50's)

Yes, no problem.