I am having a 3 1/2 inch Diam lightweight single groove underdrive pulley machined up from billet steel for A series motors. Standard pulley is aprox 5 1/2 inches diameter, the 3 1/2 inch diam will spin the water pump and alternator at lower rpm than std pulley meaning power gain and less cavitation in the water pump at high engine rpm.
The 3 inch diam is approx same size as original Datsun works pulleys.
To keep costs down I have had these costed based on a run of 10 units, If anyone is interested in having one of these pulleys the cost is $225.00 plus postage.
8 units are up for grabs.
Reply if interested.