Dear @wrm57 : Both EPA 100 are really good tonearms and in any case both needs an internal rewiring. Japan vintage analog items or Yahoo could be the best sites to look for either one.
Differences in between depends of the cartridge you mount and the system resolution but your A90 will perform lovely in either one, the MK2 is more hard to find out.
Now you could look too for the EPA 500 where exist with at least 2 arm pipes, one astraigth and the similar to the EPA 100 S shaped. Build material is similar to the EPA 100 but came with the truly best VTA on the fly tonearm ever made that's the same that comes in the 100MK2.
Differences with the 100 mainly are: bearing is not " ruby jewels " as both 100's but gimbal where the bearing friction stated lower than 7mg instead the 5mg. on the 100. I owned the 500 too and the S shaped pipe is the 250.
R.