Randall's technique was to ensure the head gasket sealed well with the liners. He recommended it for the larger bores and did it on all his rebuilds, not just those with lower liners.
Copper is an interesting gasket material. If in the dead-soft state, it compresses well...but it also can flow with heat and time. When I was into RC model airplanes, the little high compression engines used solid copper gaskets. More than once I had an engine loose compression, and when I removed the head, the copper near the exhaust had pushed out. It looked like it was made that way.
I think the gaskets we normally use are copper covered composite, mainly to help prevent the copper from creeping like a solid copper gasket does. Adding an extra copper bead around the liners should improve the "crush" and help the combustion seal.