Painless makes a good harness, so does Centech. Both are expensive
Most of the guys over at EarlyCJ5.com use EZ Wiring harness when rewiring an early or intermediate CJ5. Good product, very reasonable price.
Most of the guys have used the 12-circuit standard size:
You can find these on ebay for a few bucks less sometimes...
If you need any help/info when installing a new, upgraded harness in your '73, visit or join ECJ5, link in my sig.