Just a short question by someone who doesn't know: an expedition bike is more then the sum of its part (any well made thing should be).
just buying an 'expedition' frame (what is expedition in your mind?) and then just putting a wheelset, bars, shifters etc. that you have lying around on it does not an expedition tourer make.
you need to consider longevity, ease of repairing etc. etc. before putting something on.

Have you considered this? if so, please disregard my question, it's NOT meant to dis you or your project.