This thread sounds like wanting to wind the clock back to affordable and reliable clone motors and I don't see why it can't be done. For sure clones are out of control. A friend of mine had a pro built clone that cost over $800. It ran great and made lots of power but unknown to him there was a hairline crack in the side cover. During a race this crack grew to the point of allowing oil to leak out and before the race was over the motor ran dry and seized the rod onto the crank. You can't blame the builder, it was a defective part from the factory that only magnafluxing would have detected when new. $300 later he had the motor running again.
If you truly want an AFL this is how to do it. First, get 3-6 reputable engine builders together to write a specification. The goals would be:
Standardize on a known base engine.
Make it safe (aluminum flywheel, etc)
Set a reliability goal of XX hours of race time before requiring a rebuild.
Limit the RPM by restricting the breathing, NOT with VALVE SPRINGS! Go ahead and overkill on the springs to eliminate maintenance.
Set a cost of a finished motor less clutch and dyno tuned. I'm thinking around $350
The panel of engine builders agree on which parts to use, the HP to be obtained, sell cost, etc. These builders are the first to be certified to build and sell the AFL motors. After 12 months other builders can apply to build and sell AFL motors.
Finished motors are sealed on the dyno and the end user must break the seal(s) to remove anything other than the oil fill/drain plugs, spark plug, and air cleaner.
If you want affordable, reliable, and consistent engines this is how you do it. Once you let the genie out of the bottle by letting everyone and their dog into the motor you've lost control and can never regain it no matter how many rules you write.
I know this won't work on clone motors because clones are special. But it works on dozens of motors in other series including ROTAX in karting.
Just my thoughts, I'll go away now.