Sounds like a great idea to have Haris do your carbs. His reputation is excellent and his knowledge of these little pampers is extraordinary.
Great news about your ability to free up the caliper and bleeder line. But, you're not done! You really need to get the piston out, remove the seal (black o-ring inside) and clean the ever loving dog piss out of the caliper internal, the internal groove, the piston (make sure there's no pitting on the body) and the master cylinder/reservoir needs to be spotless.
The reservoir shoes signs of moisture, which can also mean rust accumulating on the piston inside the master cylinder, and the return holes in the bottom of the reservoir may be clogged. Look very carefully at the bottom, should be two tiny diameter holes. This is where the fluid "returns" from the caliper back up the line.
A good idea to replace the brake hoses with at least new rubbers, or upgrade them with modern hoses or stainless steel lines. A little more money, but they produce higher pressure by less expansion of the hose length. More pressure in the line = more braking pressure in the rotor.
When you re-assemble the caliper, be careful. The mounting bolts are 10mm with a very fine thread pitch. Many have crossed these up or stripped them extracting/installing them. A little anti-sieze lubricant on the threads is a very good idea. But make sure they're threading in straight. Tapping those threads sukks!
Looks like you're off to a great
start stop!
