Bob,
Unfortunately, the answer to your message title is probably “no”.
Up until about the mid-70’s (yes: 40 years ago!) karting was pretty simple. There was one main sanctioning body (the IKF) and about a dozen classes (pretty much the same classes in sprint racing and road racing). The classes were roughly along the lines of engine types/mods, and most of the “senior” classes were run at 2 weights (50 pounds apart). It was very, very easy as you could go anywhere in the U.S. (sprint or enduro/road-race) and you knew you could race. The infiltration of special interests began in the late 70’s, and Kirt described it perfectly. I don’t believe it will ever change.
Best bet is always to see what’s popular and well supported in the area where you will be racing. In the “old days” (ugh), kart racers traveled a lot more (gas and hotels were cheap), but that’s changed now. Local clubs tend to get pulled and pushed around on class rules by the people that support the club. Human nature, I suppose.
Jump in and have fun!
PM