When I orginally got my 240Z, it had the Crown kit on it. Modified in a similar way with ethanol injection. It's a Rajay turbo, which you can probably still get parts for.
I could not get more than 5PSI boost without serious detonation on my setup. It was the original L24 with an E88 head and flat tops. If you have flat top pistons, a good swap would be a P90 head, which will lower the CR, and be less prone to detonation. Some sort of intercooling would also help. I had two float bowls on the single SU to get more fuel capacity near the carburetor. The needle was what ever came with the kit.
I've attached pages from the Crown installation manual. The last photo is of my Z.
I long ago replaced this setup with an L28ET, and I have never looked back. I'm now working on a new L28ET engine for the same car.
Pete