Cheers Jon!!You and I have the same rule. I broke it for Ford GT40's, Ford Sierra Cosworth, and Porsche 911s.
Those shark noses are a good exception to the rule. Very worthy.
So far I am quite happy with my lack of discipline - nevertheless the one model rule will still be in place for my future collecting...
BTW: The GT40s are a very good reason to skip this rule too!
Must be impressive to have a GT40 parade!!!