No Ford MAFs are not calibrated for any particular injector size. The EL GT MAF calibration is not a good match for either 19 or 24lb injectors with the stock EEC, although you can normally get away with using it with 19lb injectors.

Vic, a set of 24 lb injectors and something like this:

http://www.cnlperformance.com/76mm_86-93.html

These MAFs have an interchangable sampling tube within the MAF. These can be changed to 'calibrate' the MAF to the appropriate injector by changing the amount of air that the hotwire 'sees'. It's not a percect solution but i assure you it will do the trick. So get the 24lb sampling tube and a set of 24lb injectors and fueling side of things should be taken care of to accomodate the massive increase of air you are about to provide to that motor!!

If i bought a el gt maf and put it ony my reasonbly stock 5.0 , would i see any benefit? Or would it screw the air fuel up ?

You may see a slight performance gain but it won't be huge. The EL GT, like the AU MAF will run lean up high, but its normallyonly an issue on mild to heavily modified engines.

So if i wanted to blow some cash and buy a maf, would just a 65mm AU Maf or something be cheap enough, and give a small gain?

Can you just buy the maf body and put the EL electronics on it? Or will this not work.

With the AU MAF (which is 70mm like the EL GT) you have to use your stock electronics. The EL GT MAF does flow more than the AU one even though they are the same size, but you probably won't notice any difference between them until you up around 200rwkw.

thanks heaps for that mate