66 was the first year with a 390 two barrel and 4 speed, not sure about the cyclone mine is also a Caliente but in sorry condition. I bought it with the in tension of modifying it from the get go. Sounds like yours is a nice origin an example, I wouldn't do anything you can see to that. I have a original 26 Chrysler model 70 no small block Chevy going there LOL