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many people using motors larger than this on comparable boats safely, so i was wondering if either: my info plate is outdated (its from 1971 as i said, codes may have changed etc) or if theres a difference in these boats that others are using with larger motors.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 usedJon boat HP capacity?
It is not reasonable to think that after 40 years your hull has increased in strength, and if the builder saw fit to rate the transom for up to 7 hp that would suggest that is what the boat was built to handle. While you could get away with a larger engine for a short time, you will find that the transom area will suffer damage or complete failure very quickly should you use the boat loaded and with a bit of rough weather. And in many parts of the world you can find your insurance voided and even have fines imposed regarding the over-powering of vessels. In general any authority will revert back to the manufacturers recommended hp and load ratings - and if a hull appears in poor order the default position will be to simply declare the vessel unseaworthy at all.

Probably today caution would suggest a 5 or 6 hp engine. With a fair bit of effort you could have the transom strengthened, but the hull itself was never built to handle pounding and high speed impacts, so the potential to split or buckle the hull is simply forced elsewhere on the structure. If you are not happy with the speed, purchase a hull and engine package that is rated for the higher speeds you desire.

The other boats you see may have been built of heavier material, and will have additional bracing and support for larger outboards, greater loadings and rougher conditions.

Edit - there is no way that a 40 would not rapidly damage your hull, as you have already noted the ones built for that power are far heavier and more robust to cope with the additional speeds and loadings.Jon boat HP capacity?
These are safety ratings and current ones might even more stringy. Know do note that a 7 HP modern 4-cycle motor weighs a lot mor than an old 2-cycle. I don't know of any 7 hp OB's but I would assume that if you don't load your boat to it's maximum with crew and gear that you could use a 8.8 HP without to much danger keeping an eye on your free-board when underway at all speeds, I would not use a 4-cycle over the stated HP limit. I'm not saying 8.8 is OK as it would be against good boating practices.