May as well do valve stem seals when you do the rings. The 900/1200 valve stem seals cross over to a Toyota or something and are available on the aftermarket for something like $2-3 each. (Triumph wants more like $8-9, which adds up when you multiply it by 12 or 16!) Worth checking eBay as well, perhaps.
Good rings, good valve stem seals; my understanding is oil won't get burnt when you have theses things...