Converting maps is very easy. The only real thing that you will have to do is to redo the "Mapname"Globals.kld file.
Steps:
1. Copy your official editor with the Graphics folder to your "Editor" folder in DK2 1.3 dirrectory.
2. Find the map you want to convert from 1.7 version to 1.3, say, "New".
3. Open the editor in 1.3 version, and create a new map. The size doesn't matter, just give it the same name, New. Save the map in the maps folder of dk2 1.3. It will ask you to include the Globals file, press YES.
4. Copy these files from your DK2 1.7 map folder to your 1.3 map folder:
NewMap.kld
NewPlayers.kld
NewThings.kld
NewTriggers.kld
NewVariables.kld
5. With the editor in the 1.3 folder, edit your global data. Global data holds all changes that you did in the "Configuration" tab. Simply redo all you have done in that map.
6. Save, include Global data.
You're done!
You can get the 1.3 version Here.
Thanks goes to Metal Gear Rex for some tips.