Well first of all, you'd have to limit you choice to centres. Open-play kicking in League is pretty much limited to punts in 5th down situations (or grubbers into the try zone) which means that League players don't actually have the kicking skills to play any of the other back positions in the Union game. When's the last time you saw an up-and-under or a box kick in a League game? And of course they'd be hopeless at the forward positions seeing as League forwards don't scrum, ruck or do lineouts. Frankly I think the example of Israel Folau (and SBW) sort of answers the question already. Any NRL fullback, centre or winger good enough to convert to a Union centre already has.
Greg Inglis is a popular choice and why not? He has the build and speed for centre/second five. If I had to choose someone else it would be Thurston - I wanna see how good of a #10 he would be, also he would be an ace goal kicker (even though the ball is slightly different)
Inglis.
