The March 2000 Car Craft has a lot of good info. Also, you might call AGR or Lee Power Steering. Summary: Three types of boxes are 605,800,& 808. All are bolt-ins, but manual boxes & 605's have 1 1/8" pitman shafts while 800's & 808's have 1 1/4" shafts. The two types are still interchangeable as long as you swap to the right Pitman arm. The internal stops on the box may allow too much or too little travel on a swapped box (so you may rub or widen your turning circle.
For 67 Camaro, they recommend boxes from 84-87 Monte Carlo SS, Buick Grand Nat'l,442 Hurst/Olds(ID code YA), then 92-94 Caprice Police/94 Impala SS (ID code FB), then 95-96 Caprice Police/Impala SS(ID code MX); For 68-69 Camaros, they recommend code HX, 84-92 F-car w/ perf susp/16" wheels. Codes are stamped on sidecover and end cap, but often rub off. Lee Power Steering seemed really helpful and knowledgeable, and they sell rebuild parts as well as finished boxes. Lee 818-768-0371, AGR 972-641-2090.