Update again. I had Kurt at cruiser outfitters put a load on the line and...yup...dropped to 11 volts. Culprits:
1. cig is 12 gauge wire (for sure) from the battery to a painless 1 batt hot 3 ing hot kit (cig on the batt hot line) however, the cig was body ground, not run back to the battery. I changed that last night adding a 10 gauge ground to battery
2. I replaced the wet battery with a DEKA AGM, talking with kurt it sounds like the AGM's and the old cruiser alternators don't get along swimmingly, something to do with the charge voltage being insufficient for AGM. It COULD be that my battery just isn't getting a full charge. I tried to order the alternator voltage boost fuse/diode last night but they aren't shipping out of Australia right now (money refunded...sad face)
3. Oriely ran a charge test on my system and it came up with a failed voltage regulator, which is odd since its definitely charging my battery (tested the batter, said it had a full charge) and I've also checked to see what the voltage is across the terminals when the car is running and it started at 14.4 and tapered down to 14.1 so....not sure how the regulator has failed as it seems to be, um, regulating.
In either case, I'm going to run an AGM trickle charger on it this weekend and see if that makes a difference.