This little wargamer page has a bit about Abbassid, but little in terms of historical information.
It does confirm my suspicion that the Jund-Hashid system was in place in the Caliphate, so all ordinary units (as opposed to unique units like desert spearmen, saharan cavalry etc.) can be replaced with the same Jund-hashid units as al-Andalus. It may also hold some inspiration for unit design, but I advise taking it with a huge grain of salt after seeing the same guy's "Viking" army.
Edit: what wargamer page?, you ask. This one:
http://www.miniwars.com/AbbasidArabs.html
Bookmarks