Headset/tube issues

ChrisNW There is a very small difference in headset diameters between ISO and JIS headsets. According to Sheldon, JIS is 30mm and ISO 30.2mm. Crown race size also differs by 0.2 mm too and works the opposite way (ISO dia smaller than JIS).

Therefore it stands that if you have a loose JIS headset, you could get it reamed to fit ISO instead, but you'd also have to remove some material from the crown too, unless...

...has anyone ever mixed JIS crown race with ISO cups?

Ha! I've got the same problem with my Mercian road/path frame... Mog at Brixton Cycles said I should try getting hold of an old Campy headset cuz a lot of them measured 30.2mm at the crown race and that 'might' solve the ovalised headtube, didn't realise it was just a JIS/ISO thing... Everyone I spoke to about geting hold of one didn't know what I was on about?! Nice one Chris! :)
Who makes a traditional (i.e. old skool) ISO 1" threaded headset then? Anyone got a cheap one for sale?