Having spent the better part of the day today plumbing in my new front and rear disc setup I would offer these suggestions. Cutting a 4X6" access door w/piano hinge slightly behind the round stock opening will greatly increase getting to the m/c. This is assuming that you have upgraded to a dual chamber cylinder. This gives you room to get the cap on and off and see the fluid level. A plastic bottle with twist spout makes filling the chambers much easier.
A typical m/c develops from 700-100 psi on the lines and I personally wouldn't want to trust just any valve to keep the system closed. The folding access door makes it easy to fill and monitor the fluid level and you can avoid any potential system failures and extended periods of laying on your back under your vehicle.
As for bleeding the system, I've manufactured a homemade pressure bleed system which was ok, a vacuum system which sucked air around the bleeder screws and have found that the speed bleeders were the simplest, safest (brake fluid=paint remover) system for keeping the brake system in top-notch form. It works for me because......
