The "pleasures" of silicone/DOT5 fluid. I had a bright idea years ago with my T-bucket that I should use that stuff as it is not hygroscopic and that I would NEVER have a problem. Spongy pedal and poor braking. Expensive mistake. New wheel cylinders - yeah, probably could have rebuilt them but new were only a few bucks more then a kit. new MC (same as the wheel cyl's, but...) new front braided lines. The Wilwood front single piston calipers were rebuilt, but they are not cheap kits. Then a bunch of alcohol to wash the lines, etc, etc, etc along with many hours.

Lotsa luck on your brake system cleaning