I want to install new pistons. How do I have to drill my block?
Your block must always be drilled to the size of the pistons. That means if you have pistons with 82.00 mm, your block must also be drilled to 82.00 mm. The corresponding play is already factored into the piston.
https://www.bar-tek.com/help-center/products-stock/i-want-to-install-new-pistons.-how-do-i-have-to-drill-my-block
The best is to give the new pistons to your engine builder before he starts to machine the block.