Here i have a save for the,The Hero's Long March achievement to beat 50 mission. You will only need to beat one mission for this achievement.
Instructions are in the save folder with the file.

You will no doubt need the Full Burst Disc or have all or some of the DLC in order to use this save.
please let me know if it works with out the DLC or the Full Burst disc.

I will upload a complete all missions save as well.

The Hero's long March Achievement Save File