You'll be better off finding the proper wheels.
Different lug nuts don't solve the mismatch in your hub and wheel center bore. Hub centered wheels (these are) it is important for them to fit snug on the hub. You could make bushings for the hubs but that's more trouble than finding the right wheels.
The interference with wheel and brake drum is a real issue too, also solved with the right wheels. Wheel spacers are generally regarded as a poor idea, I think particularly poor if attempted on hub centered dual rear wheels.
