Sounds like Hearsay then with the Modern Payen gaskets, I must admit I've never had any problems in the past with them, but have only rebuilt a couple of Triumph 6 engines with assistance.
Dave Kingerley is certainly worth a call, he may even be able to help with N.O.S. bearings, but his main business is Braking/steering/suspension components?
Good luck with the build
Gary