Changing shafts on X14 pros

Hi;

Last year I got a great deal on some used Callaway X14 pro irons. The only problem is that they came with the Rifle 5.5 shafts, and I am more of a regular flex player. (5 iron 160 yards) Now my game doesnt seem to suffer, but if I can get another 10 yards out of that 5 iron, I would be very happy with a 170 5 iron!

I see on ebay that Rifle has replacement 5.0 shafts sets that supposedly fit right in, and only need to be trimed to length, made especially for the X14 pros. I have built some clubs before, but am no expert, if I bought a swingweight scale, and some weights would lit be that straight forward?
In the past I just used the Java calculator and it seemed ok, but I want to set these up correctly.
Would I be better off getting one of the sponsors to do it, or is there any need to do it at all? I have heard a lot about manufactures flexs being softer than advertised, is this true with the Rifles?

I have heard that there are no dumb questions, but maybe I have broken new ground.

Thanks

Rusty