There are tools to remove those pinch bolts without all the drama. The ship has probably sailed considering the age of our cars, but on other forums members chipped in to buy similar tools then put down a deposit (to a trustworthy member) to share it around each other.
Since I'm fitting brakes soon, that I don't know if they clear my wheels, and also have to tackle the front arm problem, I've ordered a used suspension upright, complete with upper arms still fitted. Should allow me to test fit my brakes to check clearance, and see if I can fashion a tool to remove the upper arms while I've the assembly on the bench.
How much larger are your new calipers compared to the oem item ?