If your not a technical, wiring, sensors and information kind of person, dont even attempt it. If you dont mind reading lots and lots and lots and lots and lots of missinformation, contrasting methods, sensor spec sheets, wiring diagrams, dont mind doing wiring and making things and dont mind beong thoroughly confised at times then go for it
. Personally Im of the latter persuasion but I still havent finished TB'ing a mates engine after several years lol. One thing I would advise is trying to use as many of the stock sensors/ignition system as possible, this will mean having to work out how to get it all to work with the megasquirt (crank angle I seem to remember not liking the VW sensor much) but will save you the hassle of tracking down alternatives.
I went for ZX12R Throttle bodies btw, the bore spacing is pretty much spot on for the engine (and very easily modifyable to get it spot on whilst keeping the ZX fuel rail), they are pretty well matched to the airflow demands of the engine and the injectors are more than man enough for the job.
As for the mapping, once its all done and running on the road, take it to a megasquirt friendly rolling road and get them to do it for you, it will save a lot of hassle in the long run. You may think this is more expensive and that may be true, but at least it means it will run right from day one rather than being a bag of sh!te that needs constant tweekage to get it to run ok.
If I could offer you one piece of advise though, get a standard ABF installed and get that to run properly before thinking about putting it on TB's as thats reasonably well documented, gives you an imediate increase in power and teaches you enough about the system that you can progress to harder elements of the install. It also lets you know how much space you have in your engine bay for the new inlet system.
