Might consider some rust penetrant on the bleeder valves and the metal line where it enters the rubber hose. I always try to do that a day or two before you disassemble. Hit it with penetrant a few times if you can. Nothing worse than breaking off a bleeder valve or destroying the metal line. Use line wrenches also. Would definitely flush all the old fluid out when you bleed it. Your already there and a large container of brake fluid is cheap. Always keep in mind brake fluid destroys paint. I always put shop towels under the master cyl. in case any fluid gets spilled etc.

^^^ agreed & the Mityvac is looking better all the time.

I also use the mity vac to suck out almost all of the old fluid from the master if I intend to flush the system. Just leave enough to cover the ports.

I have used those hand vacuum pumps, that have a little bottle that has hose you connect to the bleeder screw and then create suction and open the bleeder and pull the fluid into the bottle, til there is no air coming out, then close the bleeder . . . usually can get at harbor freight cheap enough . . .

https://ae01.alicdn.com/kf/HTB18iXQKpXXX...-Tester-Kit.jpg

Go to NAPA, purchase Evercraft # 776-9089. Brake bleeder hose with a one way valve. Hecho en Taiwan. Best thing ever from that country.

Open bleeder, install nose, put other end in a catch can, gently pump pedal, keep master cyl from getting empty, flush it all out until clean fluid comes out. Remove hose and tighten bleeder. Do all 4 to flush the system. Don't need a helper.