Rogger,I have a 1" masonary bit.I used it to get through the CBS wall.It would be a bit more work,but you could drill a series of smaller holes in a circular pattern.Then just punch the remaining pieces of block out using a cold chisel(I have one of those also).If you are going to put both holes side by side,I also have a concrete saw,but it may cut too large an opening.You're welcome to borrow any of the gear.Darcy