I am thinking of putting a 2.3 out of a 91 mustang in my 88 sammey has anyone done this before? Im a little worried about the length of it with the auto trans. Just wondering if anyone had done it before.

Yes, I have seen this done before.  The combination is very long and heavy.  You will have better luck if you are kicking the wheelbase back.  The suspension will need to change for the added weight. For sure a major prodject.