Judging by the rule shown (as assuming it's accurate and current): "Flat head and OVH heads, and two strokes must retain the O.E.M. heads and cases", the people who wrote it know nothing about either two strokes or flat heads.
Taken literally, it is silent oncerning (and therefore permits) both later model and aftermarket cylinders on both - exactly the opposite of what they were attempting to preclude.
Again, from (several of) my previous posts:
Any person writing the rules should have some expertise in at least one of these fields, and in toto at least 1 person covering each base:
1. English grammar, spelling, syntax and usage
2. old motorcycles
3. internal combustion theory
1. is only a requirement for the final editting, but someone must be able to distinguish between "you know what we meant" from what the plain language states.
The purpose of a rule in this context (rather than a law in the criminal sense) is to prevent people from asking questions, and (if this be done) getting more than one answer.
The time-honored principle of "the intent of the legislature shall govern" is not a practical cure here, since it sends every query back to the point of origin.
Every single question raised is also a challenge to the rule itself.
If I can, by simple substitution of a few non-technical words and insertion or deletion of commas, etc. improve the quality of a rule (easier to understand, easier to enforce, fewer questions, consistent results) - and I assure you I can, it used to be my job, why are there none in authority who can either do so, or see that it's done?
2. should also be simple. I have a fair knowledge of H-D models 1930-55 (as do many others, including the original poster). I even have a chart of what parts may be interchanged, effect, how to identify, dimensions, casting numbers. What is lacking? Any sign of interest.
3. a person who does not know what function a two stroke cylinder performs should have his pen taken away from him, lest he injure himself with it.
