From what I have researched, the newer self tuning EFI systems (atomic efi, ez-efi, avenger efi, prof. products efi, etc) won't work on top of a roots type blower.
I've got a SBC running a 177 and I looked into it last year and found that unless I go with a more complex injection system, it won't do what I want it to do. I've talked to FAST and to MSD regarding their injection systems and they both tell me their system will not work on that blower.
The MAP sensor built into the throttle body housing is one factor, and the other is the needs of a blower engine is not the same as a large displacement n/a motor. So the mapping is completely different and is not supported by their systems.
The new FAST EZ-EFI 2.0 is supposed to support blower motors, but I don't know anything about it.
FAST XFI and the Holley HP EFI system are supposed to work, but they are not a self tuning unit and will have to be set up with a laptop. If I am having to do that, I might as well go with Port Fuel Injection, and that's cost prohibitive for me.
If you find something out, I would be really interested.