Doing this has raised the question about cam chain length so I've done a mock up for reference.
For the cam sprocket to fit onto the camshaft shoulder and to leave some slack in the chain, the cylinder head needs to be surfaced down to an overall thickness of approx 71.5mm.
That is measuring from the valve cover surface to the head gasket surface.
Any more than this and the sprocket will not fit onto the camshaft.
I don't know what the stock overall thickness is, although 72.5mm is the thickest that I could find.
Everything will go together without any unneccesary force and the cam chain has about 8mm of in and out movement.
This is assembled with a stock head gasket and no gaskets on the spacer.
Here are some photos with the spacer.
Mick