The stock EFI should be fine with the mods, My advice would be to get it all in and running then take it to a dyno shop and get them to check mixtures, ignition and detonation. The higher compression and extra fueling will require different mixtures and ignition to standard. The factory computer will compensate for this to some extent, however I wouldn't give it too much without getting it looked at and tuned properly.
The EFI should keep your midrange strong and really boost the low end performance. Peak power is debateable. in some cases, a natrully aspirated engine will produce more power with carbies than with efi. Peak power is usually limited by how well the engine can breath and if you have airflow meters and a heap of inlet plumbing, it can start to slow things down.
Keep us informed on how it all goes. Sounds like your gonna have some fun.