As someone who usually works with 64x models it is difficult! I think for a 64x model what I would do is do three or four pixels on the outer edges where the chest is, you can either have them straight, or what I like to do is move the two pixels closest to the centre of the body on each side up one pixel, and if you want you can add another pixel under that to make it look more full, sorry if this sounds weird to understand I can’t exactly share any pictures (I struggle with URL’s) but hopefully you understand what I’m saying! :D