It is available at this site for 650: http://www.mustangsunlimited.com/ite...?T1=PW20122+01
Anyway, Painless makes by far the best harness kits. I was unable to find another company making this product. This is probably because painless kits are absolutely amazing and they dominate this industry. It is pricey, but when all the wires are in the right places and are the correct length. You will be very pleased.
I have restored 3 first generation camaros, and the painless kits have never let me down. Let me know how it comes out. Good luck with that stang!!