I don't think they exist for the Standard engine.
From what I've read, it looks like increasing the compression ratio to 8.5:1 in Triumph applications caused the head gasket to blow out, leading to a need to increase head bolt torque. This caused the block face to warp around the head bolts, and the liner protrusion to go out of spec due to the bottom liner gaskets crushing too much. This again lead to head gasket problems. Triumph blocks use a different head bolt arrangement and the bottom liner gaskets are copper rather than gasket paper.
