Timo,
Chris has got the Offy 360° LA-Intake lying around from your old 318....send him a message, i think it´s for sale. Otherwise i´d use the crosswind intake.
Why not put a stock 5.2 Magnum (converted to carb) in the Car? They are cheap, and run pretty good. I put one together for Chris Valiant after he killed the 318....it´s running nice and smooth....would be a nice daily driver and can still do 14´s at the strip.
Michael