block advice

[Temden]

I am in need of some advice. 

I am in the process of refurbishing an old block and whilst I managed to remove most of the old head studs one snapped despite heating it. Common I know.

I have managed to drill out the old stud but in the process I fear I may have been over enthusiastic and drilled too far and gone into the block. It is the middle stud on the Valve side, as shown in the following picture. 

Please could anyone tell me if this might be terminal and the block scrap before I carry on? 

Thanks

Tom