i would recommed simply turning each clothing section into an image, and using a surface gui, put it on a model.
(it might be tedious for large amounts of clothing)
What I would recommend is downloading a 3D Rendering Software, Like Blender or Cinema 4d.
Then you can take a model from roblox (preferably r6 blocks)
Once you do that, just import the model into the software. Make a material and add the clothing image as a texture then apply it. If done correctly it should automatically match the Model and look how it would in game without uploading.