I run a couple of Goldies and i have been told by experts that unless you are going to do thousands and thousands of miles there is no point in changing the valve seats to run on lead free petrol.
I use a 97 plus octane, with a drop of upper cylinder lubricant simular to Redex, and as a special treat sometimes a squirt of Castrol R30 goes in the fuel tank.
There are lead subsitutes on the market, but whether or not they do what it says on the bottle is any ones guess.
There are garages that still sell 4-star petrol for about 130 ltr, but the problem is that you don't know how long it has been in the tank, and has it gone stale.
I will take my chances with a good quality fuel such as Shell Optimex.