Thanks for the feedback.
I've found these 2 articles which makes interesting reading:
Supercharging a 2.7
supercharging an SC
I'm pretty confident I could make up the necessary parts but if I need an EFI and ECU then its going to start getting quite expensive, plus the additional unknown of whether a 2.7 mag case will be able to handle that extra power once its all done.
Another thought, if I'm looking at an already wheezy 2.7, I wonder whether I need all the cost of 4 or 6 rib drive belts and pulleys and tensioners. Would using just a simple standard v belt with the drive taken off the existing air con pulley, with no tensioners, work (with a suitable ratio pulley on the S.C.)?
If the belt did start to slip at higher rpm then this may be a bonus in preventing the S.C from generating too much boost at higher revs.