r:
The diagrams are correct; manifolds from a W114 ('73-'74 Federal, & '73 California) are a direct fit. Manifolds from W116s, W123s, W126s, and probably R/C 107s can be used, though the head pipes (down pipes) would have to be custom.
What are the manifolds that are available to you?
If you cannot find any other head pipes, I have a new set of W116 pipes which could be reworked for your application.