You would have to rewire to OBD1 to use a Hondata ECU, because they only do OBD1 ECUs. To tune another Hondata you don't need the actual Stage 4 ECU, just the software and chip burning tools that come along with it. Also, Hondata has since updated their systems and no longer sells the original Stage 1/2/3/4 ECUs.

You may also want to look into a ZDyne Gold Super ECU, it's fully programmable (runs like $1000 I think) and I feel is superior to the Hondata because you can directly download programs from a laptop instead of continually reloading changes into an emulator and then burning a chip once you're satisfied. Plus they specialize in converting non-OBD computers.