I still don't understand how removing a large amount of block material, in the very center of the block, makes it stronger.
In this day and age of CNC machining, just how hard would it be to simply skip the cam tunnel entirely, leaving billet material filling the space?
You say you're doing this in order to mount a modern DCT without adapters? That's just a CNC program change, because you want to leave the option available for other customers to opt for a standard trans mount. So why not have a 'cam-tunnel-delete option?
Seriously, how does a cam tunnel strengthen a block?