which intake for my engine

If you can get to a swap meet or here on line, the 2 intakes I would be looking for first are the;

Edelbrock LD4B or the Peformer.

Ethier Weiand, Action Plus or Stealth is also fine for use on the 318.

The LD4B and Stealth are squarebore topped intakes, the other 2 are spreadbore tops.