Well, in the case of them being F3 forks, what is the best solution for having a working speedometer?

 

Well - the F2 engine doesn't have the speed sensor the F3 engine does. F4i digital gauge cluster upgrade might be where you start looking. That, or you throw a cheap GPS on.

Or you just figure out how fast you run at certain rpm's in what gear and commit it to memory.

 

Junky mentioned the F4i cluster, and I know a lot of guys have gone that route, using a speedo-healer, and sourcing a compatible sprocket cover with a speedo sensor - I'm not sure which bikes they usually get these from, but I know there's something out there that mounts up - maybe someone who has done this will chime in, or, you can just search the forum for "gauge conversion", or something of the like, and you might find some of the prior threads that I've long ago read and forgotten!

Another option is to go with an aftermarket gauge set, which uses magnets and a sensor on the front wheel for speed measurement - you've just got to calibrate the set for the circumference of your wheel, just like on a bicycle speedo unit... Koso is what I would recommend.

Lastly, if you don't want to have to do so much work just to make an incorrect part do the job, like I mentioned before, the seller messed up... send it back and keep searching for a '94 F2 fork set.