" I was thinking of just pulling the breaker and making the switch there."
You'd be laying a landmine for yourself. At some future date, you or someone else will assume that breaker, like all the other breakers, is in a positive line. ZZZT! in a shower of sparks wondering "Gee, how'd that happen?!" you'd remember it was the line you reversed.
Nah, this is not the place to make shortcuts. Unless those wiring runs were made with zip cord, they should be color coded for polarity, better to find the mistake and fix it.