Headlights flickering on the Country Squire

Long ago I had that problem with my '55 Chevy. It would also dim the dash lights more when I hit the brake.
Replaced the headlight switch.

 

On most of my cars the first thing to check if the dimmer switch is on the floor is the dimmer switch.. If you put in higher power headlights that can cause the headlights to go on and off and that relay is in the headlight switch.. What I do on most of my cars is wire in a relay under the hood to the headlights and the relay is activated from the headlight switch wires and take's very little to activate the relay.. Tis just what I duz..

 

For many years I owned a Class A motorhome. It still had the single 7" headlights. I customized it using quad rectangular Monti Carlo lights. Had to run them thru relays to make them work right.
Headlight switches don't like too many amps and swapping to more powerful headlights of any kind can over load the switch. .