In the latest Jegs catalog they are offering a standard 69-85 260 HP 350 crate engine for $1500 shipped to your door. I have installed several of them over the last few years and they perform well. Of course you still have to obtain the manifolds, carburetor, distributor, and the accessories but it's still the best deal out there. You should be able to source all the other engine components for less than $1000. As Bartamos stated, stay away from the "rebuilt" ones unless you can establish that it done by a reliable rebuilder.
Fred