There is no deobfuscated dev version of Galacticraft yet.
You can use CodeChickenCore for that.
Just put it in the "mcp/jars/mods" folder and turn on
"dev.deobfuscate=true" (in the CodeChickenCore Config)
This will deobfuscate any obfuscated method in the mods that you have installed in mcp.
for example: with this you can use "NEI" in mcp.