universal ignition switch

I would try to wire the charging system feed to the regulator from the ignition switch so that it is not receiving power when in START. In that way, the alternator is not being activated and loaded by the starting system and pumping out max current while trying to start; it might damage the alternator on an extended cranking session. That is a 2nd reason why the IGN1 cuts off while in START: it deactivates the charging system while cranking.