AlloyDave is correct.
Fairly soon I'll have photos to prove it. The alloy head block (80 DA-6015-AA) is different to the cast iron 76 DA-6015-AA block in mainly the dowels between cylinders 1 and 2 & 5 and 6.
The cast iron head doesn't have a windowed area over the lifter galleries, and the alloy head gasket is better laid out to clamp the smaller area of the alloy head. The galleries don't look much different between the two engines.
The block would need to have a special grove to allow the dowles to fit around the new cylinder head bolts.
On the cast iron head, the 7 left and 7 right bolts are different heights, while the alloy head has all the studs the same height.