professional products intake ???

The Edelbrock Performer (not the Performer RPM or Performer RPM Air Gap) is a better match to the 318 heads. The runners are approximately the same size as the 318 head ports and will keep air velocity up and enhancing low/mid rpm torque.

360 heads have bigger valves and larger ports than 318 heads. A 12 second 318 is going to be a very serious motor and you will have to use the 360 heads or an after market head to get there.

If you have the 360 heads I would by the one of the RPM intakes or the Cross Wind and put the 360 heads on with the manifold. Also, don't forget the cambers are bigger on the 360 heads and will lower the all ready low 318 compression ratio. Have the deck surface of the heads machined to recover the compression.