I was in your same scenario with my Batavus. I bought the knock off carb on eBay and had a buddy fab me up a larger intake. It’s not rocket science, those guys selling for $50 are doing the same thing. Find 15mm steel pipe and weld it to a piece of traced metal.
My bike has much more power than before, it was a turd with the stock carb.
Only tip if getting the knock off carb would be to disassemble, clean, and inspect it before use.
I bought the 14.12mm just to play it safe since I’m keeping bike mainly stock. Most likely you will need new throttle cable also. There is also a good spreadsheet on tuning, and what guys have done to specific bikes on this website. That way you can pick and chose mods based on what you are shooting for.
PS. Don’t let your buddies try to bully you for not buying genuine lol (edited)