I had a look into this recently. Your best bet is to use a RaceFace crank because of the compatible 'cinch' system with the Easton rings.
i.e. purchase a suitable set of crank arms only from RaceFace, and purchase the Easton spindle (the spindle is fairly cheap. It is also sold with their Powermeter which is very expensive). The Easton spindle is narrower (used on EC90SL crank) than RaceFace options.
Thanks for the response. So, perhaps Race Face Aeffect crank arms. Do you happen to have a link for the Easton spindle?