You're right, that's higher than you want (but it's also typical-to-low for these cars of this age). An ignition-loads relay, already suggested, is a very good idea (if you put it together neatly and thoughtfully with good-quality parts) that will eliminate the need to chase down where the voltage drop is in the existing circuitry, because all the ignition switch and its wiring will be doing is triggering the relayand relays take very little power to trigger.
(I have added a ground wire from voltage regulator to battery negative post.
Good. Complete the ground ring with a wire from the alternator housing to the voltage regulator base. Many alternators have a round "GRD" hole on the back half of the housing. Use a self-tapping screw to secure a wire to itmake it a short one; a long screw could hit the rotor and ruin things.
Ive noticed that when the car is running, I can pull the parking lights on and the voltage stays the same and the lights are ok but, once I turn on the actual headlights, the lights get brighter with the accelerator
This may improve to some degree when you add the regulator to the ground ring. Various degrees of weakness at idle is common with these alternators; given that you've bypassed the ammeter (assuming you've created an adequate and safely protected power path from alternator output to battery +) you can install an alternator with better output characteristics. Lots of choices; that's kind of a separate discussion topic. Note that the remanufactured and "upgraded" original-style alternators you can buy at parts stores may have higher peak current output, but tend to have poorer-than-stock low-RPM output.
