Are you sure the 4 brass-orange colors small circles in each corners arent screw holes? IF not then that could be possible but unusual for Bitmain's designs. Worse case scenario you would just have to drill holes in the Heatsink or even PCB where there are no circuitry. Please correct me if i'm wrong but there would probably be no issues there?
I can't tell from the picture, it would have to be confirmed with bitmaintech or have a sample blade.
The PCB is probably multilayer, more than top and bottom, Bitmaintech would have to supply with information where it would be ok to drill any holes.