Yes the rule is 196cc. Using either the "clone" or the GX200 Honda. The Clone is a copy of the Honda hence the term "clone".
The 212 is not quite the same, close but there are differences.
A major difference is the size (cc). a 212 is a little more than 8% larger than the 196. That's a lot.
We are changing the bore rule to NO over bore. This will help keep costs down. Like Russ stated buy a new block for 30 bucks.
All mods allowed are bolt on, no machining except carb (must appear stock) and porting (just cleaning up the intake on the short side radius is enough).
That's it. We don't need we don't need another money spending class. Buying everything new should get you into MiniPro for a thousand bucks or less. You can buy a race ready motor for less than a flywheel for a typical mower build.