I would have done a lot more checking before pulling the motor apart. If you are going to do your own wrenching you need invest a lot of money into special tools. You cannot even check or glaze break the cylinders unless you have torque plates they run around $300. You cannot check the cylinders with out them you will get a false reading!

The only difference between an 883 and 1200 is the bore. What kit was installed in it? Are the pistons dished to make sure the compression is not too high or where the heads reshaped or replaced? A did cylinder can be a hick of a lot of things that have nothing to do with the cylinder or head. FIRST THING I WOULD GET A FACTORY MANUAL.