Hmm, let's see:
Wasim Jaffer - A 'weak attack' and/or 'flat track' bully. Has a fatal technical flaw against outswingers on a good length or fuller outside the offstump (see Brett Lee). Lose him.
Gautam Gambhir - Sadly, a minnow-basher. He did well at #3 in Australia...but that was in the ODI format. I wouldn't recommend his return just yet.
Aakash Chopra - Infinitely better at seeing off the new ball than Wasim Jaffer and did act as a good foil to Sehwag - until October 2004, anyway.
Dinesh Karthik - Hmm...his average has been propped up by runs against Bangladesh. That being said, though, his average against Australia should be ignored (Mumbai 2004) and he has managed runs against a strong bowling line-up in South Africa and an average-to-above average bowling line-up in England. He didn't cash in against Pakistan, but I'm still tempted to pick him.
Rahul Dravid - No. He has a near-perfect technique, but you'd be compromising a strength to cover a weakness.
Irfan Pathan - Certainly not.
I'd go for either Karthik or Chopra, myself. If they're looking for someone to play a Jaffer-like role, then Chopra. If not, then I think Karthik should get a run. Due to the difference in circumstances, I'm not gonna vote on this one.