If you are looking to go with multi point, Edelbrock makes a real nice kit. It includes everything needed except the manifold gaskets and a fuel pump. We sell the kit for $975 and $95 for the pump.
Let me know if we can help.
To answer your question, NOTHING! It's already fuel injected. It's a pretty bullet-proof system, too. Fairly simple, and works well. Won't support gobs of horsepower, but it runs well and in my experience is fairly efficient.