1968 engine numbers, 289 or 302?

[andybud]

Hi, My name is Andy. Just joined this list tonight, hope you all can help me out with a technical question.

I have a 1968 Mustang ,new to me, with a small block. (not original) Don't know what size the engine is. I've been in a few sites but not having much luck with the engine numbers.
They are as follows: C8OE 6015A on block. D8OE , 8L1 on heads.
273AP , .60 , KB on pistons.

As far as I can tell it's a '68 Fairlane engine. (3rd digit O code)
I think 6015 means the base engine. 289 or 302?
Couldn't find anything on the heads.
The pistons are "Keith Black" after market .60 over. Again can't tell if its 289 or 302.

So,I hope there are some small block engine guys on here that can decifer these numbers or at least point me in the right direction. There may be other marks etc that I have missed to help determine what engine. Let me know where to look. The door tag is no help because the engine is not original.

Red, I hope you can help me on this one. How do you tell a 289 from a 302?

Andy