Yes I found those too. It seems they are listed in the valeo catalog for the 273, and they will swap to the slant 6 flywheel also. They will interchange, not sure on the plate pressure, but it should be a low fuss swap.
Sometimes with a linkage clutch and clutch fork on the diaphragm pressure plate the fork pivot may need to be shimmed 1/4" to 1/2" closer to the engine. Otherwise its very easy.