Jennings!
The more I read, the less I understand.
"Listen Grasshopper, when you can take the stone from my hand, you are ready" (Kung-fu)
Jennings is the master. He pulled it all together by listening to what was going on in the heady years of the early 70s and trying out what worked and didn't work. His book was like an expose of all the little secrets the racing teams didn't want you to know. 40 years later it is still valid and still a primer for anyone who wants to know Schnurl scavenged 2 stroke engines. Grasp Jennings, go on to AG Bell, do a little GP Blair for numerical theory and you are pretty much up to this millennium in theory. Now build some engines to test it out. That is what I am doing with these China Girls, cheap experiment kits to verify 2 stroke theory. Just like an electronic Breadboard Kit.
As for compression ratio and specific parts, there ain't no specific parts with these motors. Huge variety in deck heights, piston domes, and port designs. Like Jag says, they are restricted to meet the laws of most countries on purpose, and I'd add to keep price low. No need for work class uniformity. I have found the stock head is a good place to start for a high rpm motor but it is soft and I have had recurrent head gasket leaks and warpage along the plug axis under compression and any detonation. The shape is surprisingly not bad for what it is asked to do, broad rpm range power. The earlier center plug head was even weaker and cracked under detonation.
10,000rpm China Girl takes more than just the head.
Intake and exhaust port windows into the cylinder need to be opened up and raising the cylinder helped too.
Just used a stock Grubee non-catalyst exhaust too. Imagine if you used a tuned pipe?
My point was that putting the aftermarket head on reduced the rpm about 10% but increased torque a similar amount.
Steve