I agree with Croc
I actually own a Duratec and a super charger for it but I don't think I'll ever commit to going out the different side, new wiring, new hood new ECU etc.
With that said, I also happen to have an M62 if I recall supercharger that I acquired from the previous owner at the time of purchase to use on the Zetec. This is as good a time and place to ask this, but how come you rarely if ever see SC'ed Zetecs? Stock bottom end has got to be able to handle ~5 to 9 psi (guesstimating) for another 50 horse?
Shouldn't be that much different than 620R setup other than maybe a tighter fit?
This could be a reasonable solution to your problem looking for more HP without a crazy build, OP, if Croc gives it blessing.