Hy,
mechanically no problem to mount, but the 2,6 inlets are much bigger than the inlets of the 2,0 heads. So the airflow will not be perfect, you will have problems set-up the carps and maybe will not have a lot of more power.
Have you thougt of changing the engine? maybe 2,3 or 2,6 cologne V6, also was original availabe for the 20m.
On this engines your manifold and carbs deploy its full posible power

Ben! Thank you for your kind answer.
It is hard to find a Cologne V6 here in Argentina. And to change an engine is a bit burocratic and expensive
I could find a Granada 2.8 engine, but I don´t know its general conditions. Our Taunus has the original 2.0V6 with only 100.000 km and it sounds fantastic.
Our idea is to do it new replacing all pieces and doing them with a race style.
Maybe I will do the inlet manifold specially to this engine.
Any advice? All is welcome.
Cheers.
Alejandro

in that case i propose to enlarge the inlets of the 2l heads so big as possible. But take care, the material is sometimes not thick enough.
also don't forget the exhaust side.

Thank you Ben...
Have old Cologne series same troubles with oil as V4? I mean, I ´ve read V4 has some oil lubrication troubles. Thanks.

I never heard about oil problems exept for the 2.8 which is not full throttle solid because of that.
I also have the 2.0 V6 which will also not be spared (full throttle with full speed on german highways), i never had problems...

Fantastic to heard that Ben!!
You know, to have a real experience with a Cologne here is an exception.