Hi Greg, the Morrari recreation would be best suited under Historic Sports Sedans and Invited Allcomers. HSS as it is known and has a thread on this site. Co-ordinator is John McKechnie and I know he would welcome you.
They have in his group the Fahey Breadvan Anglia, the Coppins Zephyr Corvette replica and the Custaxi replica so the Morrari would be a good fit.

Cheers
Bruce Dyer