Will This Atk 351 Crate Work In Fox?

You'll need a few 351 parts to make it work- EFI intake, distributor, accessory brackets and it might not fit under a stock hood. I'd also get rid of the AOD while the motor is out in favor for a manual. A stock AOD will be your weakest link plus a power robber.

Maybe this link the moderator recently found to the 351 swap guide will help. It's not new but has good info.
http://www.stangnet.com/mustang-forums/threads/351-swap.723142/
from vristang, Oct 8, 2007
And I do not think a moderate build would need to go carb. Your fuel system could use a bigger pump, but that's easier than a whole new system. Street legal depends on your state and if you keep ALL the polution controls. But if you have an adequate fuel injection system, why run a carb on the street? Unless you like old school, rewiring and plumbing, don't go there.

There was just a discussion on the AOD and a stronger auto tranny. It was easy to find.
http://www.stangnet.com/mustang-forums/threads/89-lx-5-0-auto-trans-choices.860756/#post-8655352

FYI, I worry about breaking my T-5. My 1979 5.0 had a SROD manual that I finished off second gear in in college. The mechanic had a heck of a time fixing it so it did not pop out of second. So I am avoiding power shifts in this one.