voltage problems

i have 2 72 chevelles a 350cid and a 468cid the 350 when i start it will not start charging until i rev the motor to about 3200rpms...i assume its the regulator...my big block i have had electrical probs with for a while i thought i fixed them..replaced the ignition switch distridutor took off the 6al to eliminate it ran new wire from fuse box to ballast from a new unilite dist since i pulled the 6al...things were good the intermittant starting prob was no more...now for whatever reason the headlights guage lights dome lights all increase and decrease with motor rpms or on their own when its warmed up. i also suspect this caused an amp to blow out a capacitor (i think thats what it was) it wasnt a fuse. this i think is a voltage reg problem...i bought what was told to be a replacement regulator for $11.00 but the bolt holes dont match and more importantly the female 4 prong connector does not fit.....anybody know what i need? also is there an alternator i can use with a built in regulator?