I would also take the calipers apart and replace the rubbers. My slow-to-return front brakes actually stayed on one day! Why am I not accelerating....
!!! Luckily I was doing about 30 having just turned off an island. They quickly cooled and I took it very steady the last mile to home. 70 or more in the outside lane of the A1 in a pack of lorries with ever-tightening brakes would not have been funny
The backs of the pistons were full of gunk, also the little bleed hole in the master cylinder. You can clear this with a fine wire (0.3mm or less) though the top of the fluid reservoir. Doing these things is straight-forward. The bleeding with twin discs just takes patience moving from left to right until it all suddenly works as it should.
I didn't replace master cylinder as the bore and seals were good. Hoses are next on my list and I'll get a set of master cylinder seals in whilst I've got the fluid out to do that. Currently they are not causing any trouble, but they do have wear marks.
Oh, the only bolts that need any kind of torque are the ones that hold the calipers together. Bleed nipples, unions etc have to be snug but use a short spanner. Torque wrench if you worried. I always upset the younger engineers at work when I say I've been servicing and repairing my own brakes for about 40 years. I trust me to get it right whilst taking my time, not the garage who want it out the door!