Yeah, theres 3 main types of 20G, the fozzy ones resemble a 20K, but just carry the 20G badge.
Depending on the year foz, it'll be a phase 1 or 2 engine. I think only the SF5A was a phase 1, then they went to the EJ205 V5/6 engine.
The BG5A is a phase 1, meaning you are basically stuck with the SF5A EJ20G and ECU, though it does have a different loom (TT 4-plug, so you need to repin, as koom pointed out)...
You can convert to phase 2, but it's an arse of a job i think, it will be harder than just re-pinning.