Clubs for junior

[Wedge61]

I have a 13 year old who finds himself somewhere between juniour size clubs and ladies size. He has a set of Golfsmith Stingers, custom made last year, but he's grown about three inches since then. So I had him demo some used Lady Cobra's from CB's. He hits them quite well, and a little further than his own set, but he has to choke down to the bottom of the grips to 'make them fit'. I don't want to cut them down, because of the likelihood they'll end up being a lot stiffer and completely unmatched to one another. Question: is there an accurate way to fit a youngster who falls between juniour and lady sized sticks? The main problem seems to be getting a shaft the right length with specs that suit his swing (between 75-80 mph). Is it possible to accurately cut an "L" flex shaft to consistent "R" flex characteristics? Any suggestions/help would be appreciated.

Thanks