Battery draining fast

Okay, thanks for the regulator picture. It's the older type for a single field alternator and right for a 65. I think we're going to need a picture of the alternator as well to see for sure what type it is. You would not believe how often It turns out to be the wrong alternator/regulator combination or the thing is mis-wired. Since the car is new to you, you don't know if it was ever right. 11 to 12 volts out of the alternator with the engine running is way too low.

First, lets track down what the battery drain is and then move on to the battery charging voltage. The idea of putting a 12 volt light bulb in series with the negative battery cable is a good one. The bulb should not light if the ignition key is turned off as well as everything else in the car turned off. If it lights, disconnect the alternator output wire first. If the bulb goes out the problem is in the alternator. If it stays lit with the alternator disconnected pull out one fuse at a time until it goes out.

Hang in there, there is plenty of help available here but it can be a slow process doing this type of trouble shooting over the internet. If you have a small battery charger, put it on the battery when you have the negative cable off to keep the battery up.