“While I love detail it is an organic sound I am after.....with a liquid mid-range.“
This does rather point to an SPU, does the Luxman have, or can you add, enough counterweight to balance one? The Royal N was suggested above and of the cartridges I own I think it’s my favourite, you’d be looking at the G series though.
I don’t have an MSL, though I heard a few when I took my Transfiguration Proteus for rebuilding at Ana Might Sound in Paris and they were rather good.