Bike bodies are perfectly fine to use but have to be fitted to a good inlet manifold and fixed rigidily. Cutting up a manifold then joining with silicone pipe and a couple of jubilee clips is a complete waste of time as the bodies will be for ever going out of balance and the inlet tract will be anything from ideal.

I have used bike carbs on a C20XE and the results were mariginally better than standard but the inlet manifold was rough.