If you started with a full size 75B and did every possible upgrade to it you would probably end up at 90-95% of the performance of a tuned Shadow. That is also assuming a full internal polish/smoothing of the 75B. The big differences between a tuned 75B and tuned Shadow are the effects the firing pin block does to the trigger. The 75B having a firing pin block causes the SA pull to be a little bit heavier, adds extra pre travel take up, and a longer reset compared to the Shadow.
The Shadow II is pretty much ready to go, but still can be improved. If it doesn't already have one, an extended firing pin and 11.5# hammer spring will improve it even more. The listed weights on CZ's website will probably were it comes new. After use even a tuned action improves with more rounds/dry firing. My tuned regular SP-01 dropped over a pound in DA and about 12 ounces on the SA after a year of range and competition use.