Manual racks have different tie rod ends and require a different steering shaft.
The steering shaft can be had new from Flaming River for about $75. If you're reeeeeeeeeeaally lucky, you might be able to score one from an older (like '84 or older) Foxbody, but the chances of that are slim to none.
Don't bother with used tie rod ends, of course. Score some new ones from a parts store. Have them look for those for an older Mustang ('79 to around '84) when manual steering was still available from the factory - most likely on the four-cylinder models.
Also, just curious, but what are you doing (or have already done) with regard to the routing of your serpentine belt with the power steering pump being gone? Do you still have the A/C compressor there to loop over on the driver's side, or are you running one of those funky alternator tensioner brackets to bypass everything else? Just curious, as I'm considering going manual later on (funds permitting), since my power rack and P/S pump are both drooling fluid...