I actually think he would probably have signed Lukaku. Played the right way Lukaku is a Fergie striker, he's much more similar to Andy Cole/Hernandez/Owen than he is to Jose's ideal striker Drogba. Whilst players like RvP, Cantona & Sheringham were capable of playing as target men, he didn't really utilise them like that. A striker who plays off the shoulder of the CB's, like Lukaku, was usually his preferred option. I also think Lukaku would have thrived with Sir Alex's style of management.
---------------DDG---------------
Valencia, Jones, Smalling, Shaw
------Pereira, Kante, Thiago-----
-----Zaha, Lukaku, Rashford----
It doesn't look the most overwhelming side on paper but Fergie teams rarely did, especially after the CO92 had finished. But it has plenty of homegrown players who understand the league and the club, and it'd be largely a hardworking side with plenty of pace and combativeness. It'd also be much better than we currently are.