I'd rate Pollock above both Steyn and Bond and I would rate Akhtar above Bond, 18 matches and less than a 100 wickets is barely enough to constitute a career. Although having said that, if I could have, I would have picked him in my NZ round.
I think I agree with you
Just looking at averages doesn't tell the whole story sometimes, you've got to look at who they played against and where. In that regard, Bond had a relatively easy career. About half his Tests were against Zimbabwe, Bangladesh, West Indies and Pakistan - and you can see that if you take that half away he averages about 30 against the other 5 teams. But that also means he averages about 15 against those 4 I mentioned, so he was really good at exploiting lesser batsmen and that shouldn't be discounted too quickly.
Shoaib's career on the other hand featured far more matches against better batting sides. Just looking him up...and he had to play 34 of his 46 Tests against the best 5 batting teams: Aus, Eng, Ind, SL and SA. Look at his average against them and it's about the same as Bond's - 30ish. So the difference in averages really just comes from Bond's demolishing of Bangladesh and Zimbabwe, which makes up a decent percentage of his Test wickets. It's a shame Bond never had the chance to play more against the best sides to prove that he might have been a better bowler, but we'll never know. So if I had to say who's had the better career, I vote Shoaib.
Steyn vs Pollock is a bit closer though. Steyn has had to play a higher percentage of tougher series than Pollock did, but Steyn's average is also deflated by the way he's destroyed Bangladesh, New Zealand and West Indies which make up a larger percentage of his career wickets. Against the top 5 sides, their averages are about the same. Gun to my head I pick Pollock because he had a longer career, but Steyn can certainly go on to be one of the greats.
All that said, the new ball pairing that I'd rate very close to yours: Donald and Asif