I discovered that you can have portraits that are larger than the 142x96 size. I think it can be up to about 355x230. But if you make it that large you will have text overlaying the portrait and it won't look as good (it won't be symmetrical). If it's larger than about 355x230 you may experience CTOD (at least in MTW 1.1) and the portrait may "wrap around."
