I bought a '78 Malibu a few (6) years ago. Incredibly low mileage (29,000), 305ci 4bbl, TurboHydramatic. It had been stored in a collection display for many years. Took it to MVD emissions testing and of course, it failed ~ needed tune-up.
I took it to a Chevy dealer, since I didn't know any decent old school technicians, and after all, this car was barely out of warranty (not counting its age). The dealer's service manager asked me to bring it back the following week ~ the only technician they had left on staff "who knows carburetors" was on vacation. Nobody else knew how to tune it without fuel injection or a scope and a code-reader. Took it back the next week, the old-timer was back, he worked his magic, and the car cleared emissions . . . in fact, it hardly registered on any of the scales! All these years later, the emissions guys always remark on how clean it runs.
Drove it to Denver from Phoenix for a roadtrip in a hot July . . . high altitude, mountain passes, air conditioning on full blast the entire way . . . and averaged 23.8 mpg. At the time, I had a "fuel-efficient" Taurus 6 cyl company car that had trouble making 22 mpg on the low plains.