I would get get fitted - both lie board and launch monitor - and decide what shafts you need from there.
Then, do the math. Golf shops start at about $10 labor per club for reshaft, plus the cost of the shafts. Assuming 3-PW set, and using GolfWorks 2011 catalog costs, reshaft would cost you:
- KBS Tour (S): ($25 shafts x 8) + $80 = $280, plus grips
- DG S300: ($14 shafts x 8) + $80 = $192, plus grips
- Project X Rifle 6.0: $269 for set + $80 = $349, plus grips
Not sure if you can sell the pullout R.flex shafts or not.
I am assuming these are the Pro Combo irons from circa 2003, the ones with the punch-hole pattern in the lower back of the clubhead. If this is the case, be aware that that they have an MPF = 337, which puts them in the Classic/Player's playability range (not a lot of forgiveness).
You're a 6 HDCP, so you need to decide if you like the original PCs well enough to reshaft. You might try reshafting the 4i and 7i and see if it works.
Also consider the 2011 VR Pro Combo irons which sell for around $900 at a golf shop near you.
Like everything in golf, it's you call.