Jon boat HP capacity?

so i have a 1971 ouachita jon boat that i use for fishing on decent sized lakes in the area, and the max horsepower that the information plate says the boat will safely take is a 7HP. so the question is, i have seen/heard about many people using motors larger than this on comparable boats safely, so i was wondering if either: my info plate is outdated (its from 1971 as i said, codes may have changed etc) or if theres a difference in these boats that others are using with larger motors. im not trying to be some kind of speed demon or something out on a little fishing lake, but its just annoying when i look for a larger outboard motor (using a minn kota trolling motor for now) that i have to stick in the lower HP range, which tends to be more expensive when used