I have worked with arduino in other projects and I believe it will be an easy fit.
I will start with a ecu swap and after everything is working fine I will try to add compressor and other features.
I purchased an speeduino version 4c from ebay although I haven't understand the difference and now I am reading and planing my next steps.
I believe a wide band is my next purchase to make my life easier.
I was thinking to use suzuki trigger and distributor to minimize fail points.
Also I am trying to find stores that sell ecu sockets as I will like keep the roll back option.