Assuming a 94 is much like a 92 I know that the stock rubbers fit the new manifolds and the Keihins as I have two sets. The ones for the older 900's that used Dellorto carbs and have 2 rings instead of three (I have a set of those too
) They fit, but aren't optimal.
As said above, make sure you have the grooves right. The manifold gets the single grove side and the carbs get the double groove side.
When installing the manifolds you will have to start the nuts with the manifolds pulled back a bit from the head in order to get clearance. Make sure they are centered over the port before your final snug.
My bike came with two identical split downdraft carbs. The cables come with two 45 degree fittings and two 90 degree fittings. The 45's go to the vertical cylinder and the 90's go on the horizontal cylinder. Make sure they aren't all twisted up, the rubbers turn to accommodate this. You MUST be sure they operate freely before you start the engine. Check it lock to lock as well. The pull cables go in the third hole on that side of the 5 holes on the wheel and the push cables go in the second hole from their side. You may need to install the pull cable on the vertical cylinder before you mount the carb in the manifold. The other three cable can be mounted with the carbs in place.
The cable kit throttle pin is supposed to fit in a hole on the handle bar. Again, I don't know if that hole is in the factory bar, or if you need to drill it. I have two now and run my cable a little differently than they were to accommodate my double brake line and keep the cabled from hitting the interment pod. It all fits, but it's like adjusting the steering stops on that bike; a compromise between what works and what you'd like.
You may want to remove the tops of the carbs and put a drop of nail polish on the nut and screw that are for synchronizing the carbs when run side by side. As I learned on here, you don't need them for split carbs, but they can come loose and will mess up your syncronization.
Because mine came on the bike I'm not sure what the fuel line routing will entail for you, but I suspect you'll need hose, clamps and a tee fitting. Keep the hoses off the engine.
The flat head screws in the manifolds that mine came with are a b***h to get out to install the synchronization tubes. I switched to socket caps and still ended up cutting a key down to work.
As stated above, synchronization is critical, just did mine tonight and it made all the difference in the world.