[TR] Decking late TR6 engine block?

[aribert neumann]

The later ('72 or '73 & up) TR6 engine has a thicker compression ring about
each bore with a corresponding recess in the block (about 0.025 inch
deep).  What happens when the block is decked (approx. 0.015 in.)?
Kastener's Comp Prep manual makes mention of decking the block but no
mention of what happens with respect to the recess.  Anyone know?  Anyone
have their later TR6 block decked?  Milling the block enough to remove the
recess to be able to use the earlier head gasket would remove so much
material that the pistons at TDC would be above the surface of the block.