Looks like a Solex intake/exhaust combo from down here.
I've found that light porting cylinder/piston w a dremel to be the most rewarding and productive enterprise. That said ive gotten a solex to slightly faster to 21 or so.
Sadly gravity on atomized fuel has little to do with increased performance. Looks badass though including the stock carb, down draft. We all wanna go faster by removing restrictions but a 10mm intake can do 30mph easy.
Problem is the carb throat i think its 8mm. If u switch carbs how r you gonna control the overflow like the og carb?