My beetle's been sitting for a few years, and currently in the restoration process. Replacing the brakes, but all the brake lines look to be in good shape, just wondering how, or if a DIY person can flush out the crap in the lines. Same goes for the fuel lines.

This should help with your brake problem:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563-5.html#post619000