High Charging Rate. Found Voltage Drop Need Guidance Please

You measured the high side of ballast, and got 11.4V. Same as IGN terminal of regulator. Measure that with engine running, increase engine speed some, early alternators may not reach regulation at idle. If voltage is around 13.8V regulator is good. Replacing will not help over voltage.

I think your battery seems soft already. Hot weather, 15V at battery will spew acid, and sulfates plates.