i tend to think that it's brazing-related distortion.
i can neither see nor feel any distortion of any sort in the head-tube, down-tube, top-tube or associated lugs. i looked and squinted in bright sunlight, used a flashlight...whatever i could come up with. also, the smaller front-to-rear dimension in the ovalized lower end of the head-tube is the same measurement as the (the still round) upper end of the head-tube.
a CR member suggested that if there's any play when installing the lower cups to use JB weld to fill the gaps (and painting the inside of the headtube first to act as a release plane in case i decide to remove the cups later).
whew!
walter manning
metro-detroit-area, michigan