As I posted in bvy's Fun with Multigrade Filters thread, I damaged an old #3 Ilford MG filter in the 6x6 inch (15x15 cm) above-the-condensers size. The center is usable, but ... I have an even older set of Ilford MG filters. They go from 1 through 7 (seven filters) in single grade steps. The damaged filter is a member of a set of 12 filters that go from 00 through 5 in half grade steps. What would be the nearest equivalent of the newer #3 (damaged) in the older filter set?