Ok, the horse has bolted on a sympathetic recomissioning of the engine, given that you have already started it and this picked up a fair quantity of whatever crud was sitting int eh bottom of the sump and run it through the pump, into the filter, and possibly beyond.
Please do add a sump gasket to your purchases and take the sump off and clean it out inside, this is a good opportunity to find out if dire things are happening as is usually evidenced by metal fragments, clips and pins being found int he sump. Please note that the sump gasket does not need ANY sealants, adhesives, or magic potions to do its job, all it needs is a nice, clean mating surface. If you are having trouble getting it to stay in position whilst you offer the sump up to the engine prior to bolting it - a small smear of axle grease is the way to go.
Brembos have hard anodised, polished pistons and unless they leak when connected to a working master cylinder I'd be inclined to leave them alone other than fitting new pads, new stainless steel bleed nipples and some new rubber caps. I would count on replacing the hoses to the brakes as soon as practicable, this is a near 40 year old machine and they have had their life. Braided stainless steel lines are good.
After the length of time your bike has sat, you can pretty much bank on the master cylinder being toast. Pull it apart and if the bore is undamaged, clean it up and put a new piston kit in it (and then go and buy a handful of lottery tickets). OTOH if the M/C is toast you have some decisions. If it is a "round" tank model, it is junk purely because you can no longer buy new tanks, I have several otherwise serviceable (or repairable) round tank M/Cs and I keep looking but cannot find new tanks. Even if yours is good it is still a time bomb as the seal at the base of the tank will fail and when it does it is game over because whilst it is just a simple O-ring, pulling the tank will destroy it 99 times out of 100.
If you have a square tank, then I'd buy a new tank (they are cheap) and O-ring, and possibly a new internal "baffle" (which are not cheap but are eventually ruined by brake fluid). Look on the front side of the M/C and it will have a number, most likely 12 or 13 which refers to its bore size. I would pay to have a square tank M/C sleeved in stainless steel before I'd buy a new one - the stainless sleeve will last forever and require only piston changes thereafter and will cost a lot less than a new M/C. There are some who say a sleeved master cylinder may leak - in which case it was done wrong. Correctly done the sleeve is frozen and pressed into a heated M/C body that has been previously bored to size - the resultant interference fit is NEVER going to leak. However, a brake cylinder rebuilder who does not have a precision lathe on the premises is likely going to use a bench drill and should be wearing a white cap and a black apron because he is a butcher, not an engineer. Using a bench drill and adhesives works sufficiently often that many use that method and frankly with a sleeve going into a cast iron cylinder, yeah maybe. Into Alloy - no way......
If you do buy a new M/C, buy the latest brake lever as well, it may help you avoid a mismatch problem.
That needs to be cleaned and relined urgently. I've no knowledge of POR products, but a lot of people report positive results. A small tip. Once you have your new liner in the tank and you are about to put it aside to cure, lay it down upside down. The reason for this is that you inevitably end up with a "blob" of excess liner material and if that blob is always under fuel you run the risk of the fuel attacking it and getting through it to the steel and restarting the corrosion problem. Putting the tank upside down means the blob is permanently above fuel level and is less susceptible to attack.
Buy a rebuild kit, they are cheap. Also buy a new filter "sock" for it - that is the only fuel filter an airhead needs.
Before spending a fortune on new parts, these carbs are VERY durable. If you have the "pissing fuel on your boot" problem, firstly turn your fuel tap off when you stop - your carbs are not petcocks (Bing told me so). If you have a persistent leak, take the float bowl off and jiggle the floats up and down a 1/2 dozen times and see if that cures it. This can take a while, I foolishly let my fuel system dry out and when I went for a ride last weekend I had to stop 11 times and do as above until all the crap in the fuel lines was flushed through. Obviously if you still have problems after the above, put a kit through your carbs. Do not wimp out on replacing he butterfly shaft o-rings, they are important. Do one carb at a time as many components are "handed" - mixing handed components is bad....Very bad.
Further rant later.