All grades of gasoline, including premium, have 10% ethanol. The sign on the pump says so. Unless it's advertised as "ethanol free" you're just paying extra for slow-burning gas that isn't needed in any engine with less than 9.5-10 to 1 compression. 1980's engines, unless they have been highly modified, were built to run regular, but exactly NONE of them came from the factory with solid lifters. What's the gauge pressure you get on a compression test? If it's less that 175 PSI or so, regular will work just fine. You might need to make a minor adjustment to the ignition timing.
Jerry
