I agree with Mike. Got a unknown 318 for free. Guy said it was from a Dodge Diplomat that was rusty beyond repair.
Was sitting in his backyard. Did just what Mike said. Sealed it and did the heads.Ran it in my truck. Used a quart every 250 miles and blue smoke when cold. Drove it daily and it actually got better with use. That was over 10 years ago. Still driving it. Uses about 1 quart 1500 miles.No smoke at all.Worth a shot if you don't want to spend allot.