The people doing the casting didn't know in which vehicle the block would end up. So there's no way that a 318-3 engine would have anything cast onto it that signified that.

Your number is just a "dash number" which has to do with the casting process as mentioned above.

There are no magic dash numbers like some people think. With Mopar's spotty casting quality cylinder wall thickness, for example, can be all over the place. So if contemplating a high(er) dollar build, the first step should be checking the cylinder wall thickness.

I think you got a smoking deal! It's at least a good core. Given the toughness of the 727 it may be a bolt in and go part. The shift points are, as mentioned above, most likely at a lower rpm than a passenger car. Maybe John Kunkel will tell us.

R.