Here's a couple of options.
Here's a link to a scale conversion chart. You could have a commercial printer blow up the 1/72 scale decals to 1/24 scale and print them on laser decal paper, which you would have to supply.
http://www.wwi-models.org/misc/scalecon.html
Or, you can contact Mike Grant at www.mikegrantdesign.com/decals He can make custom decals from your 1/72 scale decals, picutes of your 1/72 scale model, photos of the actual a/c or whatever documentatoin you have.
Good luck.
Jim