I'm worried I'll drip brake fluid all over the firewall and frame when I install the freshly bled master cylinder. I assume the fluid will be dripping out as I work to re-install the lines. Is this true and does anyone have any suggestions?

 

It doesn't leak out that much. I think some judicious use of plastic sheeting and keeping a few clean rags handy to clean up would work. You could go overboard and "mask off the firewall under the master cylinder with some plastic sheeting like the kind painters use, you could also cover the frame below the same way. I don't think the brake fluid should damage the paint if you clean it up quickly.

 

Most rebuilt or new master cylinders come with plastic plugs to screw into the brake line connections during installation. When you pull these to install the brake lines, very little drips out. I put a shop rag beneath the master cylinder. No issues.