Cruise control was an option in 67, just not on a Camaro. All GM lines use the same RPO codes, but each line only has a certain group of these RPO's available.
As far as rareity or value, it depends on if it's real. After the 69 Z28, the 67 Big block is the next favorite car to clone. Tons of fake L35 and L78 trim tags out there. No big of any kind made before January of 67 so if it's earlier than that you know right off the bat it's not real. Most (not all) big blocks are April or later, as it took a while for people to figure out they were available and start ordering them. Have to see an image of the trim tag and know what the VIN is to make any kind of opinion on originality.
Let's assume it is an original big block, in that case it's rare just by being a big block. Only 4000 out of 220,000 Camaros built in 67 were L35's. 1400 of those were Autos, the rest had manual transmissions. Every (factory installed)option adds to it's rarity. Is it a 4 speed or Auto? Standard or deluxe interior, does it have power brakes, guages, etc. Does it have a radius rod on the rear axle?
