Hi Mark,
Generally when driver sizes are specified, you use the purple line, so the diameter includes the foam surround, as KCarlile and others have already noted.
Sometimes I've noticed that manufacturers interpret driver dimensions rather broadly and include the widest possible dimension to the outer edges of the basket.
While it may be fun to buy kits to add new surrounds to drivers whose foam surrounds have deteriorated, don't expect the speakers to perform anywhere close to their previous standards. The elasticity/damping of a driver surround is carefully specified during its design and re-foaming can never hope to duplicate those standards.
It's certainly OK to get an old pair of speakers working again, but in my view, nostalgic memories of cherished old speakers should remain that way. Besides, I've found that when you drag a pair of those much beloved old speakers out of the closet (I have a fair number of them) and put them into a controlled double-blind A/B comparison with really excellent modern speakers like Axioms, many of the old speakers sound truly awfu and very colored. It's astonishing the progress in speaker design and fidelity that have taken place since the 1960s and '70s.
Regards,
Alan
