I don't think obd1 will change something for your emissions test. I would definitely stay obd0, with a PR3 as anassa suggests or a PW0.
Is your "cat" still good, maybe buying a new one will be the most helpful solution, a worn cat is like nothing for emissions. Honda ref is 18160-PW0-G01 for 91 CRX SiR cat converter, tho I don't think you'll like the price...
Last solution we use sometimes, if you ecu is chipped, have a friend tune you a "lean" map you use only for emission test...
