I made a mistake and used your criteria of 2003-2008. Should have used 2007 tbf, cos that's 6 years but it doesn't change much- same wpm and better average.Where did you get 329 from? 1Jan 2003 - 1 Jan 2008 he took 287 wickets. Around 70 of which were against Zimbabwe and Bangladesh.
Imran had a much better run and didn't make the team.
You can't just ignore minnows, but even if you do he's still taking 7wpm @ 21. Possibly the easiest 5 years for batmen ever. Look how insanely far ahead he is of everyone else:
Bowling records | Test matches | Cricinfo Statsguru | ESPNcricinfo
SR, total number of wickets, WPM, average- he's ahead on everyone in every category pretty comfortably, even if you compare to the best of them, not them individually.
What qualifying period does Imran look better in? 287 wickets isn't that far from imrans career total, and he had a long career.
There is definitely no bowler that has ever bettered this. No bat has, except maybe Bradman, which is really difficult to compare. Maybe one of the allrounders has him beat as well, but I'm not sure when, particularly considering the constraints of periods. Kallis had a ridiculous 2003-2007, with a ton of runs @ 67 with the bat and 87 wickets. I'm not sure if another allrounder can beat this, but it beats any specialist since Bradman, other than Murali, who still takes it pretty comfortably IMO.