[JimmyMac]

Peter,
IMO................
The transistor kit might have been good on the day.
I had a choice of both types when I got mine from one of the original GT40 builders and he recommended the dual point.
Most of these old governor boxes are dead when you get them and the rest are on their last legs. So for $600 a pop, it's not worth it. The empty boxes also go for that price for the concours car builders.

The later solid state ignition relays are much easy to get and I'm told that the modern remakes of these are even better.