My advice is to consider an AT120E for the SME. This cartridge isn't suitable for massy arms, but a fixed head SME should be fine. Use the black-tac that SME used to supply between cartridge and headshell, aluminium screws (no need for heavy stainless steel bolts here) and track at 1.5g approx. This should open up the sound nicely I think.
By the way, any other modern cartridge tracking at 1.75g or more may just upset the RP3000 servos, as the OEM Matsushita direct drive motors weren't as good as the ones fitted to their best decks in the 'pre quartz' era.
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