Vintage patterns have challenges all their own. One of which is figuring out what to use if a yarn is discontinued.
Sometimes a pattern gives you a gauge to work with so you may be able to work out a substitute....
Sometimes you are working blind. That is where the fun begins in being creative and breathing new life into vintage patterns.
This chart of discontinued yarns at PurpleKitty.com can be a great resource. Have a look and book mark it for later use.