Personally, I've got a 90 LX so for me it's a Foxbody, but right now you can get a 94-95 fairly cheap, (redheaded stepchildren in the mustang world) the sn-95 has a lil bit longer wheelbase so there's that, but everything else is the same as a 79-93 mustang. Do the subframe connectors, upper and lower suspension reinforcements, along with tubular control arms (adjustable if you wanna get into it), do a coil over front suspension to save some weight in the front. Since you wanna run an automatic, which is the best way to go IMHO, use a built C-4. You can get those built proper with a reverse valve body and a trans brake that will handle 1200 hps with a lifetime guarantee and yes they are available with a BBF Bell housing. The 8.8 rear end when treated with the proper gears, axles, and differential is more than adequate for the power range your talking about. With the proper build, as long as the suspension is done right, the upper and lower torque boxes are reinforced the way they should be, frame connectors welded in proper, ect,ect you get the idea... You'll be able to beat on it and it'll do well.. Of course you'll find things to work on as you go.. But that's the fun part, Right??