ACE @ # 7: a hearty +1 to not buying more cheap unsupported crap.
Get the pre-sorted Mikuni or the Amal, or simply make the MikCarb work with Hitchcocks jetting chart. Carbs are just so stories, once dialed they work well. You can pull a lot of hair out becoming a carb tuner, or you can get the sorted model and enjoy riding the bike. Fine tuning is one thing, starting from scratch is another.
Two-strokes are completely different engines, the intake mix gets gargled through the carb more than a 4-stroke does. The needle jets are different for one thing, often they hade "shields" on them. Without ready access to a box of tuning bits specific to your exact carb, there's a lot of guesswork involved. IF you can find another fellow that has a 28mm PWK on a Bullet AND has tuned it to run well AND has recorded in detail the exact internal bits used, you yourself can spend a large block of time rediscovering the wheel.
A new OEM MikCarb is about $100, the tuning path is well trodden, parts are readily available from H's to compensate for intake & exhaust mods. Both of mine work well. Unless you are running a forged piston, steel rod & needle bearing con rod and routinely winding to 6,000 RPM striving for HP, the 28mm MikCarb is good enough. For about $200 you can get the Amal, already sorted, well supported, with maybe a better choke system. The Mikuni is the same story but with better parts. I'd sort the MikCarb and go riding.
https://accessories.hitchcocksmotorcycles.com/accessory-shop/carburettor-kits/38529PART No. 90086 ; CARBURETTOR KIT, MIKUNI 32mm (1989 - 2007 500 Bullet) ; £249.00
This is a genuine Japanese made 32mm Mikuni carburettor with all the necessary parts to fit the 500cc Bullet. It will give improved performance over the standard carburettor. The kit comprises of a Mikuni carburettor, special manifold, S&B air filter throttle cable and spare jets etc.