[Lynn Eades]

Hi Malcolm, I could get shot to pieces here but here goes.
You a not likely to hear the ping in a carrier. Too much track noise, fan noise etc.
Yes the carrier will labour while turning in second gear (depends on conditions. Soft is worse)
As a rule, all turns involving the brakes are executed in 1st or 2nd gear.
When you brake one side, immediately the other side has to turn twice as fast.

The vacuum brake should have just a small amount of drag because it stabilizes the cam (dampens out the "rattle about" of the points cam) which makes it fire evenly.(and when it's supposed to)
The dizzy was designed around 68 octane fuel, you are probably running fuel in the range of 91 octane. It probably won't ping anyhow, because of the modern fuel.
Lets see what others have to say.