No, there is no maximum image size that can be uploaded.
Run.GPS will resize the image upon uploading and this is probably where it has problems with memory overflow: to resize the image you have to put it in main memory. If the image is very large, memory size may be exceeded.
I'm trying to upload trainning lasting 27 hours and 100 kilometeres with 12 images (my phon makes 8 mpixels pictures) and run-gs crashes during upload. I have galaxy note 2 with 2 gb of ram. Any solution?