Well, think about how open-ended your question was.
"Crate engine" means any engine that comes in a crate. There are as many different crate engines as Heinz has sauces (probably more, even). You could be talking about a generic $1300 rebuilt engine with no manifolds, damper, or even oil pan or valve covers; or a $20k turn-key 540 CID big block. What you would "need" with those engines is completely different
Be a little more specific, and not only can we give you useful information, we'd be glad to. | 
