hi pmac, out of curiosity do the pistons sit high because you've had the block skimmed?
or are the pistons just too high anyway because they're aftermarket?
Both reasons you mentioned contribute.
Every engine we build is different. Most of them are non standard spec/component.
Putting an all stock Nissan engine back is easier but ultimately boring.
The components used ie piston, cam, headgasket are all factored in the calculation.
There is block to piston and valve to piston clearance to think about.