I have made a solution to this problem!
1.first you need to download the Halo Mac Full Bloodgulch from HDM.
2.after download throw the Mac Bloodgulch in your (downloaded or bought) PC full Map folder.
3. now Converting will work! Just select your PC Full Maps folder when you click the button: Full Maps
(then click the converting button duh)
Hope this helps!
Mac Full Bloodgulch: http://www.halodemomods.com/wiki/File:H ... dgulch.zip

(Red highlighted is the Mac Bloodgulch with the PC Maps)
Credits:
Modzy for making Pearl
Sparky for giving the topic name for this tread.
Bungie for making (Both) Halo Full.