E30 Zone

I'm trying to make an inlet manifold for an itb set up. How far away from the head/inlet valve should I mount the throttle bodies?

Depends on a few things, what size are the bodies, what length inlet runners are you planning on using (total length), what engine are they going on, can and compression?

I'm planning on using 38mm throttle bodies. The total length of the intake will depend on what clearance I have. The engine is a standard 2.5 at the moment but will eventually be tuned. The plan is to get it working and then spend money on the motor. I want to mount the throttle bodies as close to the head as possible so that I have plenty of scope when trying to find the length that works best. How close is too close?

Also what cam are you going to use, and it´s timing?