Lots of oil pressure switches have the low oil pressure switch built in. So it’s just one port.

Stainless steel manifolds, thin wall stainless will crack. It’s not a case of if it’s a case of when. Just weld it back up.

The in thing for budget Zetec turbo manifolds is the standard mild steel manifold from a crate engine. They are cheap and easy to modify and being steel they should be a little more durable.
Again I am not a fan of the cvh manifold with adapters, will it even flow 400 horses ?

Hydraulic hoses fittings are usually steel. I wouldn’t really fancy using them on your vey soft welded alloy An fitting.
Alloy push fittings are fairly compact.

I thought you said in your other post your injectors fitted fine ?