Where can I find a guide for swapping a late model rotary engine from a Mazda into a NSU R080?

There's no book, all you need is the engine with all ancilliaries including the complete wiring harness, transmission and radiator, some decent fabrication skills and plenty of free time. It won't be easy but it can be done. You may also need to change the steering system due to the difference in the overall engine dimensions and resulting position.

And to find a NSU Ro80.

I have two cars that were converted. Works well.