Sometimes the few components attached to the firewall are moved to the other side under the dash. You could also make a decorative "box" to locate these items if you plan to use the vehicle as a daily driver and want to be able to access them without having to crawl under the dash.
A Corvette style master cylinder can be used under the floorboard with a remote reservoir to keep an eye on the brake fluid level. That will make things look a lot cleaner. As far as wiring goes, you can route the wires so that every wire follows a single path rather than having wires going everywhere. You can run the wiring bundle down low where they are not easily seen.