Chris, I'm not sure if its been suggested before but have a search around on
Sign In - Aussie Elises and see if any Lotus Exige or Elise seats are for sale.
They are small (nothing is much smaller than a lotus) and would be ADR compliant but check with Treeve our cobraphile friendly online engineer here. People used to suggest MX5 seats but lotus's are smaller.
Also, in a coupe they'd be perfect moreso than in a cobra.
Might be worth a try.
Spookypt