Classic/Antique Car Repair: 1930 Mod A cutting off when brake applied, tractor supply store, brake light switch

Question
I have a 1930 Mod A Ford.
1. The old battery needs to be replaced. Where is best and economical way to
find a 6 volt for 1930 Ford? Local AutoZone, Cal Ranch, etc?
2. It stops when the brakes are applied. My Dad says it's probably the brake
switch and to get a new one? It sounds like a short somewhere, but I didn't
put the car back together, my dad did. Any easy testing to locate short or to
test switch? Best to just get switch and see if it works?  And if switch is most
likely, where can I get one? Thanks for helping?

Answer
Find a tractor supply store.  They have the 6 volt battery at a good price.  Sears also has them.
You can get parts at snyders, bratton's. or many other suppliers.  Join MARC and the Mag will get you to all these people.  The brake light switch is very simple, located under the floor boards.  You say it stops when you step on the brake.  What is wrong with that?  Do you mean it shorts out?  If so, just trace it with an ohm meter until you find it.
good luck
jack