@mofimadness : thanks for the suggestion. I reached out to Michael at britaudio. He does not handle FR64S tonearms. So, I think I'll do the workaround like @jasonbourne71 mentioned (I had already planned this option) and just build an extension cable from the too-short interconnect. Not ideal, but it will hopefully suffice.
Fidelity Research FR64S Interconnect Replacement
Is it difficult to replace the interconnect on an FR64S? The one on my unit extends only 4" out of the base. It's difficult to access to attach another interconnect to get to the preamp. I can't find photos on what the disassembly steps look like. I also don't want to mess up the tonearm that's otherwise in mint condition.