good on him for making such a courageous decision, but i really cant see any position in nfl he would be better than the thousands upon thousands of guys over there who have been working towards it their whole playing lives.
pretty much any position i can think of he could possibly play he is way behind what is out there. as a running back he is not the sort of rushing, low centre of gravity, tackle busting type, nor is he fast enough to be used in the way teams would a wide receiver back there. punt returning is also very different to kick returns in the nrl. again, he isnt as fast as a devon hester, et al.
only position i could see him with any chance at all is free or strong safety as someone else (happy?) said, but then those guys are speed freaks as well. only strong point for him in that position would be he can tackle. another thing is how incredibly harsh the refs are with pass interference and flags in general, he would have a very hard time adjusting to.
again, kudos for having a go, and i would love to be able to sit here and watch him playing in the nfl, but realistically i cant see him playing in the super bowl any time.