rsx2002, I'd imagine it would be an y easy swap if you could find one ... but have you loked at the ratios? It would not be surprised to find the final drive ratio for both 5 and 6 speeds is the same.
Honda gears its manuals fairly low. I think this is so you can use cruise control at 55mph-65mph and still pull long hills on interstates without downshifting.
I wish they wouldn't, but I'm afraid that's the case.