Looks like Danny has given you some great info. I still use a cable driven tach set up and like it a lot.SW 535AH tach with the Mopar tach drive distributor,and I have a vintage Accel BEI tach drive unit to use if need be.
Glad to see you're using the cable system.
Nautilus Racing- We use Superformance gaskets and Turbo Action converters/products.