383 deck clearance
The only way to know deck clearance is to actually measure the piston down in the hole if it has not been blueprinted.
If you do decide to have the block decked, it needs to be done on a fixture that precisely locates off of the main journals and indexes the crank/cam centerlines, and also gives an accurate referrence for the actual deck height.
Of course, if you are going that far, make sure the block is honed with a torque plate because the bores will move, and if one isnt used the rings will not seal properly.
The only way to know deck clearance is to actually measure the piston down in the hole if it has not been blueprinted.
If you do decide to have the block decked, it needs to be done on a fixture that precisely locates off of the main journals and indexes the crank/cam centerlines, and also gives an accurate referrence for the actual deck height.
Of course, if you are going that far, make sure the block is honed with a torque plate because the bores will move, and if one isnt used the rings will not seal properly.