Block Milling

The pistons I bought are gonna be fifty down in the hole. How far down can I mill the block to get more compression if I need it? Can anyone tell me what the compression will be with the following set up?

360 bored forty over
Magnum heads from 98 Durango ( will be surfaced and 2.02 valves installed
Felpro head gasket
Speed pro flat tops with four valve reliefs at fifty down in the hole

Is that all the info you need? Thanks guys.