The best place might be Yamaha MusicSoft, but you may want to expand your searches there by varying the model number to include the precursors to the PSR-E463.
Other than that, there are many, many style files that are available for free from this forum's main site, and collections on USB which Joe has put together that you can buy to help support the site.
In any case, you'll very likely need or want to "massage" and tweak the files to make sure they're in the correct format (SFF1), don't contain any unusable variations (C and D), use the best voices available on your PSR-E463, and so on.