I went down the complete 280zx donor car path. Much easier as already stated because everything is there for you including the engine.
Like the ebay ad says, your head also wont be suitable because it doesn't have the notches for the injectors.
I used pretty much everything off the 280, ECU, loom, dizzy, manifold and fuel pump. They pop up every now and then rusted out beyond help going cheap. Either that or an old skyline or 280c.
Wiring up isn't so difficult just have to pretty much find some switched power to supply ECU and fuel pump relay etc.
One problem I ran into was with rego where they wouldn't pass it with a pod filter unenclosed.
I ended up getting and airfilter box from the US from a 280z which makes it look like it all belongs.
You probably still have the 260z carbies on it though and a swap to the 240 style is always a much easier option with good results.
Good luck with it