To put some numbers to the swap:

The tires 29 to 33 tire swap reduces the stopping torque by 13.8%, the calipers increase the front brake torque by 11.1%

The stock caliper piston for the single piston calipers for a 1990 V6 has a diameter of 2.246".

The four piston units for a 1997 3.5 L Montero has 1.684" pistons and an area of 2.23 in sq X2 (two pistons) or 4.45 sq in.

The single 2.246" piston has an area of 3.95 sq in.

Kevin

87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...