Combining Chryco and Mopar, Look up the blocks factory deck height.
From Ramchargercentral:
BLOCK DECK HEIGHTS
B = 9.98"
RB/Hemi = 10.725
So what engine are you building? Are you using factory stroke crank and rods? Can your machine shop measure from the crank main bores in the block to the block head gasket surface?? If they can, then you will know if the block has been decked already.
You know the crank stroke, and rod length. Piston info from the manufacturer will include the compression height.
So take half the stroke, and the rod length, and the piston compression height. This number will equal the deck height of the block if the piston tops are flush with the block deck, and the block has not been deck cut already.
Most factory pistons are below the block deck with piston at TDC. Usually it works out well to have the piston tops flush with the block deck (head gasket surface).
You can get there, just need some more info.