Use Kroil on the valve stems, squirting a liberal amount on them and letting it sit a day or so before starting, then add a little (3 or 4 ounces) to the oil. You'll probably have to bite the bullet and get a valve job done but Kroil would be the only thing I'd consider using to free them up without a complete teardown and guide cleaning with a rotary wire brush.

www.kanolabs.com
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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