The nose profile of the Esci F-111's is wrong. Is is too wide.
The Hasegawa F-111 is your best bet in 1/72 but you are really only likely to find them on Ebay these days and have to pay silly money to get them.
The Airfix one is pretty good shape wise too but lacks in overall detail, and again they are pretty hard to get hold of.
F-111.net is a good site for references for the differences...... http://www.f-111.net/ext_diff.htm
F-111A's and F-111C's both had the Triple Plow One intake with the splitter plate and translating cowl.
F-111D/E/F/G and FB-111A* all had the later Triple Plow Two intake . (* except the first 2)
F-111A/D/E/F all had the short span wings, while the F-111C/G FB-111A all had the longer span wings.