I guess the Chuck Hawks article is http://www.chuckhawks.com/28gauge.htm . Maybe, the article refers to current shells on the market that are readily available.

Have you found 65mm shells?

I suppose that brass hull makers could supply 65mm.

http://rockymountaincartridge.com/Price_List.pdf shows for ten hulls:

28 Gauge 2˝............................... $50.00

Gotta find some load data for that brass - RMC probably can come up the a reference.

Reloading for Shotgunners 5th Ed by Rick Sapp might have 65mm load data - it has data for a lot of different shells.