Gary sez: "Power factor correction caps connect between L1 and L2. The
value
is whatever reduces the 1 ph line current from the service entrance
to the lowest value. Again experimentation will be required. Do this
*after* you balance the converter, if you're going to balance it. The
value won't be the same for a balanced converter as it will be for
an unbalanced converter. (Usually, it'll be smaller for a balanced
converter.)"

Right on, Gary! The 2 key points in Gary's closing paragraph are "do this
after you balance the converter" and "reduces the 1 ph line current from the
service entrance to the lowest value" Important here is that the current
from the service entrance is measured with a clamp-on type of Ammeter.
Unlike the voltage measurements for balancing this is a current measurement.

Bob Swinney