Does the rod have a fixed reel seat, or is it a Tenn Handle style (no reel seat, retainer rings holds reel on) ?? If it's a Tenn Handle, then you can move the reel to a position where it balances better (once you find the right reel).
Looking at the weights of the reels mentioned, I'm thinking the CS5 @ 8.3oz might still be a little too heavy ... since your son's Garcia weighs about 8.6oz (and your Sahara weighs 7.6oz)
If possible, take the rod to your local shops and try a few different ones on it and see which one balances best. I'm thinking something in a graphite frame in the 1500-2000 series with a weight of around 8oz.
(reel weights are just what I could find from the limited info of brand/series)