Tail light and dash lights short

I have a 1941 Master Deluxe, but the lowest in year was 1961 for this site. The car had a new Ron Francis harness installed for the original six volt system before I purchased it. I recently upgraded to twelve volts with an alternator, replaced all bulbs and so on. Only issue I had was with the taillights and dash lights, which are wired together or on the same fuse, a ten amp. This fuse began burning up or popping as soon as I turned them on. The front park lights are on a separate fuse, as are the headlights and both work great.
I ran a voltage reducer for the gas gauge, which also works great and even a better response than when on the six volts system. When replacing the bulbs, I took them to Napa and they matched the six volt bulbs to twelve volts bulbs, basically by physical size.
So I have e a short someplace. I was wondering if it could be caused by too much amps being pulled by the six bulbs, the two taillight and four dash or simply something grounding out? The bubs Napa gave me for the dash are marked as fourteen volts, not sure if this makes a difference with my twelve volt system.
I read another post and response regarding a similar issue with a 1980's Escort. The response directed to use a light bulb temporary wired to the appropriate fuse to assist in finding the short. Hopefully mine should not be hard to find since I do not have many wires, right, lol.