The lead was used as an octane booster. There was a side benefit of valve lubrication. Assuming the gasoline you are currently using has the same octane (and the same caloric content) then no calibration changes will be necessary.
As to the lead additives:
I don't personally use them (nor will I). If the engine ever requires rebuilding, I have the machinest install hardened valve seats, which totally eliminates the problem of valve seat recession in any except the most over-stressed engines (possibly a tractor plowing in gumbo soil, or a pickup pulling a 40 foot travel trailer???. Others may have differing opinions.
Jon.
