I have a mark 75 (Barn find) that I’ve done a 100% teardown on. Slowly, I’m putting it back together with fresh parts as needed. I’m questioning the cylinders/pistons though. The service manual states that the factory bore diameter is 2 7/16″ (2.4375) I did a comprehensive bore measurement with a telescopic micrometer at top and bottom of bore stroke, and checked for roundness. Across all 6 cylinders, everything is pretty much 2.440″ with .0005″ of variation at times (half thou) Which in my rookie opinion seems pretty good. The potential? issue i have, is the mice that nested in the exhaust side of the head pi$$ed in a few of the cylinders, so there is surface rust that needs to be honed out. When i measure the piston skirts, they are around 2.430-2.434″ which puts my skirt clearance to almost .006-.01″ right now, without honing……So the long short of it is, at minimum, this block needs a scuffing and new rings. At maximum, it needs a .015″ over bore done, (i have Wiseco pistons for it) however I’m struggling greatly to find anyone in the west Michigan area that is able or willing to bore/machine hone blind cylinders, and i don’t want to risk ruining a block if the specs i provided are well-worth just working with a scuffing and new rings. Any expert advice would be appreciated!