Drum brakes actually have more braking power than disc when cool since they have more area of contact between the shoe and drum than there is between disc pad and rotor. My swap to discs came not from heat but from weather. We were going through Kansas City during rush hour and a monsoon where the right side drums were under water for miles. Brakes went away completely on that side so the discs were on the front before the next trip. On ones that are driven only in nice weather then factory is fine but the old Buick gets driven in downpours, blizzards, sand, mud, or anything that passes under it's wheels in any kind of weather. It is really nice when you put your foot on the brake under any conditions to actually have stopping power. I know most old rides don't get driven around 8000 miles a year but for ones that do upgrading is a sound choice.
