For your first build I would get a flat mount. This way you don’t need new carb.,intake etc. Just leave govner and all linkage connected. You can hook up a throttle to the linkage ( do some searching). 212 is plenty out of the box! People want to jump into getting a fast bike and rip and tear into the motor then can’t get it running right. So leave it stock..plenty of power,!
I have 2 projects. Like you, one is a Predator 212 build. Right now, hopefully Harbor Freight sent me the engine. They don't ship to Hawaii, so I had to freight it to Carso CA, then to me.
So my project's more in the planning/researching/acquisition stages.
What kind of bike and transmission are you using?
Im doing a Sixthreezero extended cruiser w/7-speed cassette.
My idea is to use a jackshaft/shift kit, and transmit brute force thru 7 speeds.....
using timing belts and pulleys.