Xantia, new engine wanted

[lux]

My 1.8 16v sx is consuming a crazy amount of fuel, i get about 450kms per tank
I noticed it is sucking air where the fuel injectors are, so i will see and change the o rings. I will also see around if any other leaks are present.
My question here is, in case i end up opting out for a engine swap, could it be replaced with a Peugeot 406 one, as understanding that it's the same xu7 engine code.
I am confused about the hydraulic pump placement, should any machining be done in that case?
Also, are the servo pumps interchangable?
Kind regards
Luka

[xantia_v6]

The engine block and head is the same as a 406, but most of the ancillaries would need to be swapped over.

The 406 probably has a steering pump where the Xantia pump sits.

Your fuel consumption is likely due to air leaks.

[lux]

Any regular hotspots for air leaks?

[CitroJim]

Any regular hotspots for air leaks?

Anywhere south of the throttle body and everything connected to the inlet manifold. Especially small rubber pipes...