Well, quite apart from the wiring issues there is the problem of physically locating the engine in the engine bay.
EA-EL have different engine mounts to AU-BA.
AU-BA have an integral cast alloy sump that fouls on a EA-EL K-Member (you cannot swap sumps as the mains cross-bolts go through the sump).
I have looked at swapping in the full AU subassembly (suspension, alloy cross members, steering and engine) which I reckon is doable but a lot of work. I have never seen this done.
Another alternative is shown here;
where a Kiwi has managed to get an AU engine into an EA up and running (so it can't be too hard)
I reckon you would be better off starting out with a front-cut rather than with the pieces already stripped out of a car.
There may be Smartlock issues to consider as well.