I dont have EFI so perhaps you'll get some more comprehensive answers from some of those guys.
But, I would be looking at articles like this:
http://www.airflowresearch.com/artic...le087/A-P1.htm
to see if this sort of thing appeals to you or if you can take something from it.
Personally if I were going to this much trouble I'd also go for a Cam from Ford Racing (say E or F303)- good bang for buck - and upgrade the
oil pump and add a main girdle if I thought it would regularly see 6000+rpm. That's just a reflection on my comfort zone.
A number of guys in out club have converted to a more traditional single plane carby manifold with a 4v throttle body and have had good results.
The advantage of an upgrade like this is that a lot of your existing drive train and fuel system can probably cope - not sure about injectors/ECU.
Good Luck with whatever you choose and make sure to take lots of pics to update us on progress
LoBelly