The only carbs I know of that have the same spacing as the TK26 cv's are the TK27 cv's from the ZX 550 A motors, and the TK22 mechanicals from the first-gen KZ550 motors (KZ550A1-A3, C1-C4, D1).
The TK27 is a direct swap.
The TK22 requires you to modify the intake manifolds. The 2nd gen motors have the same carb spacing, but the manifold bolts are farther apart. You just have to notch out the bolt holes on the manifolds (aka carb holders), then use thick washers on the bolts. You may want to convert to stainless allen screws that are a tiny bit longer to make up for the washers. The only other issue is that the ports are bigger than the manifolds. There is enough wall-thickness on the manifolds to cover the ports, but that change in diameter puts a step change in the intake tract which leads to the accumulation of gasoline under certain circumstances. This just means jetting can be a little trickier. Jetting evaluations are better done over a long period of time so you can get to know how the carbs behave. Obviously, because they are mechanical carbs, you can no longer just mash the throttle.
Z1 enterprises has new carb intake manifolds from the early motors, which is what you would need to install the TK22 carbs on a 2nd gen motor. Unfortunately, it looks like the price just took a huge jump up.
www.z1enterprises.com/ItemDetails.aspx?item=16065-1014X4
