Higher grade brake fluid is specified for 1967 c50, so is probably yours. Higher brade br fluid as higher boiling point, & better flow charastics in cold weather. There are big bolters that use DOT 3. However; if you plan on haul'in a lot of weight with frequent braking, I'd consider using better fluid.
Do you have any idea how long it's been since the master cyliner resivour has been empty? How long since breaks were last used? Did they work? If you're un sure if the brakes work. I'd use DOT #3 just 'cause it's cheaper $. Then when brake are working, I'd upgrade the fluid later.

Also; Due vacuum booster(s), Be sure the engine is NOT runing when you bleed brake lines.

Welcome aboard

CFFC
Don

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