That's about it unless you do a Magnum head conversion. I wouldn't suggest that, because it will require a different intake manifold. Also, The Weiand Action Plus is much better than the performer.....just my opinion.
The Performer will clear the hood better in some cases especially if you plan on using a Thermoquad. Plus the Performer gives a little more bottom end vs more top end for the Weiand just my experience. Both are good intakes or a 318.
As far as the head conversion is concerned I would just swap to a 5.2 Magnum engine if you can find a good used one and that way you pick up the Magnum heads, roller cam, and a block that should have better core shift as well. JMO.