74 super beetle electrical issues?

hey everyone my beetle does this "surging" where it feels like it missfired but it only does it at high RPMs and when it does it the RPM guage goes nuts like when it does a surge the needle will jump up even though the RPMs on the engine havent. and today it did the surging really bad and the battery went dead so i couldn't start it. also the headlights will get brighter and dimmer as if it was switched between high and low beams but when i hit the switch they will dim so i know its not actually switching between high and low beams its just getting brighter and dimmer and so on... i took the battery cable off while it was running and it didn't die and the headlights worked so im sure its not the alternator. could the voltage regulator be bad? also could these issues be completely seperate from one another? any help is greatly appreciated

I kid you not,
The PO of my 69 routed the tach to coil thru the drivers seat rail. It wreaked so much havoc! But it just fried stuff. No surging.
My DD is having voltage reg issues. Do the lights pulse at idle? Yep. I saw that. 74 is internal? Believe so. A good alternator shop should be able to repiair it in a few hours. Provided you remove and install it.