Where is the distributer located? Front passenger side or the back centered? If in back, how are the spark plugs oriented? 2 Pairs angled toward each other on each bank? Or 4 evenly spaced plugs, all angled the same?

It's not uncommon to have a 361 or 383 two barrel...both of which are large blocks...and the distributer would be in the front of the motor.

There are two varieties of 318's, the "LA" and the "poly".

The LA is the traditional mopar small block with the pairs of plugs angled toward each other. 318's small blocks didn't first appear until the 67 model year, iirc. If you find that this IS what you are looking at, pull the valve covers and see the numbers on the heads...it should have either 273 or 318 located on there somewhere...a more sure way is to find the casting numbers on the block....it'll say the ci's right on the passenger side, toward the back/oil filter area.

The poly is sometimes referred to as a "wide block" because it IS, in fact, a wide block...and many will call it a large block because of its physical size. I don't think cars saw them after 66...some trucks may have though. Certainly one of the first motors to use a canted valve head made popular by the chevy "rat" motors later on. The canted valves don't help flow all that much, so the 318 poly was never a crazy wild motor...although a dual quad, 290hp version was available in the late 50's/early 60's iirc.

hope this helps...post up what it is.