Most light problems can be directly related to bad grounds. Grounds don't like rust and they especially don't like new paint and powder coating. I would clean all contact areas and use star washers and new hardware as a starting point.
Also the brake lights go through the turn signal switch so that may be a place to look.
Fred

Last edited by rfs56trk; 07/15/2017 7:56 PM.

1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine