Center drag link, are they really $600? 1964 dart

Good advice above.
Put the engine in the car, and find out if you have a problem! (Do yourself a favor, throw in a bare block with mounts and a pan on it.)
It fits? Fly it
It don't fits? Modify something.
Me? I'd buy a deeper triangulated sump milodon pan, and "adjust" it (hammer or welder, I'd weld in a channel to clear the link) till it fits. So what if there's a little oil captured behind the channel/hammered area. Add a pint.
It would not be the first oil pan I modified. Or the second or third.
There is no f-ing way id pay more than a hundred bucks for a centerlink.