Edited while you posted, reread. All parts/lines should be replaced, all new fluid, I know you hate to hear that. Skimp on the dangling fuzzy dice, not the brakes.
Originally Posted by bartamos
Full of gunk? Be careful not to re-contaminate with dirty rears and gunky lines, master cylinder. Flush is iffy and can just move gunk around. SNAFU recipe. 30 years means it is FOR SURE all rusty gunk from condensation/absorption and decomposed internals.

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