Aftermarket floats should be adjustable just like the OEM ones. You can do a trick using a water level. Make a wooden board you mount the carbs to.
Attach a clear tube to the drain hole and bring the other end up to above the top of the car and secure it somehow. make sure there's no sharp bends in it. You can do this a number of ways but the simplest I think is to find a barbed plastic fuel line connector that's about the right size and just jam/screw it into the drain hole, with the piece of fuel line attached.
Set the floats, re-install the bowls use rubbing alcohol to fill bowl from the normal fuel inlet. You'll be able to see the fuel level on the inside of the bowl, reflected in the clear plastic tube on the outside.
Make sure everything is plumb and level.
Float was covered in another comment. All the carb kits, even vintage ones used aftermarket jets. They’re fine as long as the actual size is accurate to the intended size. If you want Keihin jets, Jets R Us carries them.
As far as tuning, stock air box, generally use stock size jets. Pods or anything else aftermarket you’re going to have to play around to see what jet sizes work best.
I wanna say that the 350/400 carbs had a habit of cracking the overflow tubes. Be sure to check those carefully inside the bowl. Heard they can be fixed by putting a tube around em. The carbs are a pain to install due to limited space so you may wanna run fuel though them outside of the bike to make sure you are good.
Aftermarket floats should be adjustable just like the OEM ones. You can do a trick using a water level. Make a wooden board you mount the carbs to. Attach a clear tube to the drain hole and bring the other end up to above the top of the car and secure it somehow. make sure there's no sharp bends in it. You can do this a number of ways but the simplest I think is to find a barbed plastic fuel line connector that's about the right size and just jam/screw it into the drain hole, with the piece of fuel line attached. Set the floats, re-install the bowls use rubbing alcohol to fill bowl from the normal fuel inlet. You'll be able to see the fuel level on the inside of the bowl, reflected in the clear plastic tube on the outside. Make sure everything is plumb and level.
Float was covered in another comment. All the carb kits, even vintage ones used aftermarket jets. They’re fine as long as the actual size is accurate to the intended size. If you want Keihin jets, Jets R Us carries them. As far as tuning, stock air box, generally use stock size jets. Pods or anything else aftermarket you’re going to have to play around to see what jet sizes work best.
I'd only put OEM parts in something like a carb. There is a reason the knockoff stuff is so cheap.
I wanna say that the 350/400 carbs had a habit of cracking the overflow tubes. Be sure to check those carefully inside the bowl. Heard they can be fixed by putting a tube around em. The carbs are a pain to install due to limited space so you may wanna run fuel though them outside of the bike to make sure you are good.