Any way to get clean older versions of minecraft? Specifically 1.2.3 for modding purposes

I'm looking to install Sonic Ether's Unbelievable Shaders which requires Optifine which requires a clean minecraft.jar file. Unfortunately, I patched mine with the HD textures and Optifine doesn't seem to work. And since 1.2.3 is the only thing compatible with both mods and it is not the latest version, Is there any place where I can get the 1.2.3?