My actual Iron master cylinder is 7/8 and I think the booster is one diaphragm while the 88 V6 models have 15/16 Master Cylinder with a double diaphragm booster. I think it will be a good idea to swap since I already bought a brand new 83 (small) disks and shoes for the front brakes.

Anyone has changed the master cylinder with booster already?

Thanks

JorgeA