I did that hose clamp modification myself on my white 412LE - had no problem!
One just need to be careful not to damage the electric terminals (and there are a lot of them), when removing the engine. If one of the sensors or the altitude regulators don't work, the whole system fails. Contrary to popular belief, the ECU box (fitted inside the body panel, below the right centre windscreen, and about the size of a 500g Omo box), hardly ever fails, it is the connections that give problems. The little plastic screw on top of the ECU is used to adjust the fuel mixture.
I think I might still have a spare high pressure pump for you somewhere, will have a look then you can have it
