Timmy's made me think of another option - programmable ignition. Being able to get the timing much nearer the money than you can with a clockwork dizzy will give a good improvement in tractability everywhere as well as reliability & economy.
Metty Turbo had a 3.2 FD which, I think, was resurrected on the SPI Mini.
Light flywheels are near enough essential on racers, where getting to the first corner in front of the competition really matters. As has already been said, the benefit is a lot less dramatic doing road car type stuff
