I had the same quadry so what I did was cut off the compressed pipe clamp to the right angled plastic connector and replaced it with a jubilee clip, in that way it meant I could do the O ring removal and fitting to the plastic housing on the bench.

Then connected the right angled connector to the oil cooler got that on securely then fitted the pipe and tightened the jubilee clip.

Much easier that trying to fit the O ring correctly at full stretch with the risk of dropping it and also that spring clip on the connector itself.

Also there is very little space to manouver that connector with the pipe attached.

Cheers.

Andy Fuji White / Jet 2012 4.4 TDV8 Westminster

sounds like a decent approach, you go with wee Dremel style cutting disc or careful hacksawing diagonally?

If I remember the standard clamp is one that has some latching tabs that latch it in a loop and a special tool tightens it, so then you can just find the join and prize it apart using a small flatblade screwdriver.

Andy Fuji White / Jet 2012 4.4 TDV8 Westminster

If you go on ebay and search for the engine, you will see quite a few engines for sale that have good front end photo's that might point you in the right direction.