David - the best way to start (if you haven't already done this) is to make a master
negative out of your MacBeath chart or other standard color reference, expose it either under tightly controlled studio conditions, or outdoors under mild white subdued sunlight using the exact correction specifications of your color meter, along
with precise exposure compensation per exact 100 ASA. Everything we do needs some kind of calibration, and Ektar is fussy about getting off on the right foot to begin with... My own tests were standardized to the latest Fuji CA II paper, which
seems to hit its sweet spot with about a 3X or 4X magnification ratio per the standard neg (though actual subject shots will obviously differ in contrast). I control
this up or down through silver masking, but if you attempt this, the tricks are a bit
different than masking for either b&w printing or Ciba. You might have a problem
with too much contrast if you are contact printing. You can take a step down using
portrait paper (Type P - discontinued, but still plenty around), or take a step up in
contrast using Super C (also discontinued but still available). These papers are not
quite as clean in chroma as the new Type II but are still pretty good anyway. Or you
could just shoot Ektar selectively in more limited light ratio settings analogous to
how we have successfully shot chromes all along. You'll get on the road pretty fast.