I was just browsing the cylinder head tech article and got blindsided by this:
Intake/Exhaust manifold bolt pattern
The 1971-1973 A12 differs from the A13/A14/A15 and most A12s after 1973 except wagons.

Scared the crap out of me because on first reading it seemed to say that the manifolds were not interchangeable between original 1200 A12's and later A-series. BUT, then I saw this right above in the same article:
Intake Manifolds
All A-series heads will interchange with either type of intake with the following caveats:
Those caveats being the coolant ports etc. I was aware of those differences already.


Heres the pic illustrating the differences

So whats the story? I want to use an old Canon manifold for Weber DCOE (designed for 1200 A12) on a later round-port A14 head. I want to combine it with a purpose-built aftermarket header, also for A12. Is this going to be a bolt-on? I can fabricate anything I need to - but I did not realize there was a bolt pattern difference.

Any experience here?

Thanks all!