Are you sure you aren't talking about the Model M? The Model F is capacitive and NKRO. They might be hard to come by, though, as they were pretty popular around here for awhile.
The Model F is certainly not manufactured anymore, but Unicomp still makes the Model M under a different model name. You may want to PM treivelot (sp?). He is in Australia and he might be able to help point you in the right direction. IIRC, he is a big IBM fan.