"What should be obvious to any engineer is that the Nuclear Pulse AutoGyro can be very lightweight. It's use of reaction balls, with large deflection angles and centrifugal force, would absorb and counteract the forward thrust of each detonation as easily as a massive pusher-plate would, but with far less mass."

But was the size of the mass of "massive pusher-plate", a problem in in the Orion design?

The problem with rockets is getting them above the atmosphere- I assume this thing has to begin to operate once out of the atmosphere.
Therefore what this thing should be compared to is the second stage of a rocket.

And I assume that rather than mass lifted, this thing hopes to provide a relatively small payload a very high velocity?