HS crown cone interchangeability question
 

acquired a Hatta Swan HS in really good condition at a great price.
the only woe is that it has JIS crown race, 27.0mm. obviously my fork would need ISO 26.4mm.
while i don't want to give up an opportunity of having a nice high-end Hatta HS,

thinking of finding an interchangeable crown cone, that would fit here.
(Hatta do have 26.4 crown-raced Swan HS, but they don't come with part by part.)

my initial and naive thought is that if any from a Campy-copied style HS could fit with no serious problem.
there's no 'sealed' or any sort of fancy additions here. straight-forward '80 style HS we are talking about.

see some cheap old Schwinn branded cones and Tange Levin ones easily on the web at cheapo price.
there's also a DS crown cone (fron their Pista line) available on Loosescrews.

bought a cheapo on on ebay already to try it myself,
just would like to get any knowledge or anything to keep in mind etc.

any insights or experience would be appreciated.

How thick is the crown race (dimension "M" below)? What size bearings does it use? If you can match those two parameters, it should work.

http://www.os2.dhs.org/~john/headset.jpg
Source: Sutherland's 4th Edition

awesome. thanks!