I think I'd take a short term pain for long term gain approach.
I will admit, it is very risky, taking both Salem and O'Rourke before the bubble, but if you get away with it could pay off well. It will also put you on the border line of round 8 exposure, and you would want selection to go your that week. I think it presents the best possibility for you to move up the rankings during the byes though. If you want to target a top 2,000-2,500 season result go the upgrade this week. If you want to risk dropping your season to top say 5,000, with the hope of pushing into the top 1,500-2,000 arm yourself with some cash for the byes!
Just a Word of warning on Selwood. He will possibly have a reasonable sized B/E in round 9, and he plays Freo that week. Freo are his "nemesis, and he has a worse record against them than anyone else. I will admit, I haven't investigated reasons for this, and someone will probably throw up a concussion affected score to explain it in part. His price could nearly be bottomed out in round 10, where he is due to play North, and expected to score better.
Good luck