The cast iron intake will work just fine for a 318. Port match if you wish. I like the slightly later factory spreadbore intake, IMHO it's a real high rise intake. I matched the intake port on three sides because I had the time but it's not necessary

The Offy Dual-Port was a novelty when it was built It sounds better than how it works. It was supposed to aid fuel economy. Put it on ebay and someone will bid on it for sure.

Steve Dulcich tested one in his 383 intake shootout and it was a dog.

R.