I have read many articles on modifications to increase horsepower for the 240Z.

Nobody seems to offer a scale of suitable mods showing horsepower gained with the level of modifications done.

I run my car in hillclimbs and sprint events but also like to use it on weekend runs.

I apparently have an L24 motor with N42 head, SU type, round top carbs and 6 into 2 extractors with 2 and half inch straight through exhaust.( I have not opened the motor to check the internals yet)

This engine revs to 6500 rpm before running out of breath. Torque seems to be in an even band from 2500rpm. The addition of an electric fuel pump has helped deliver fuel.

Does any one know what the next level of tuning should be?

I have not had this engine dyno tuned so do not know what it currently produces.does anyone know what the next level of tuning should be?

try putting a zx distributor on it and a new 50,000 volt coil. Not an expensive upgrade if you have a salvage yard around you. Get the e12-80 type. It's very easy to install, and works great.