<VV> VDO Gauges-charging system

[shortle]

Hi All and Merry Xmas,
On my journey this weekend of about 750 miles in my 1963 Rampside w/ 1965 95 HP PG, on my newly installed voltmeter, my gauge readings about 90% of the time would read very close to 15 volts whether cruising or idling,lites,fan,stereo on or off. The other 10% of the time it reads about 13 volts. Although I have no indication at my battery anything is wrong (no loss of liquid present, battery feels cool)I have verified what I feel is an overcharging condition using a seperate hand held voltmeter.
I am using an internal regulator delcotron recently "rebuilt" (by me) using an American made kit purchased from Checkers (a great deal if the parts are a good 
quality-$15 for new brushes,bearing, regulator,etc.).
I have new battery cables (purchased from 1 of our vendors),my main junction point is off the starter positive cable going to a seperate positive junction point,my main lead going to the front does NOT go through the multi pin connector, I have no voltage drops at any of the pos. or neg. cables,and I have extra ground cables all around my vehicle.
Another part of the saga is this is the reason I "rebuilt" the delcotron in the first place. I thought for sure I would solve this issue after finding it had a regulator that said "made in Costa Rica".
Is there anything I am overlooking in this alternator? Can any of the "hard parts" be causing what I feel is an unhealthy and abnormal condition in the charging system?
Finally, I intend to install my cylinder head temp. sender unit under an old snap switch on the left side head instead of installing it under a spark plug. Thank you Seth for the recomendation. I'll post the results of that afterwards.
By the way, I was very lucky with the weather going from Durango to Santa Fe to Albuquerque to Gallup and then back to Durango.
The only other problem I encountered is my odometer sometimes will not work on my original style cluster.
Again, happy holidays to all.
Timothy Shortle in Durango Colorado.