Have you seen what the linkage looks like on one of these things? It would be hard to replicate if the manifold doesn't come with it. I had a Z28 crossram on the first SBC in my Horizon and aside from using more gas I didn't see much benefit. I think it did raise the RPM's about 400 but it robbed power from the bottom end. It was polished and looked purdy. This one not so much. I think that price reflects the fact that there is no linkage.
Has anybody told you that you spend waaaay too much time on CL?
They make repro Linkages, bro! And yes, they're a lot of fun to set up. Did it on a Max Wedge a long time ago, but cool???OH YEAH!

Yeah, I do spend some time on there, I tripped across it looking for something for Aryan1

(And a replacement pool pump motor......

)
Did ya pick up those mounts?
Ray