For a solid axle rear? Torque arm/PH setup, 33 spline limited slip with beefy axles, a good set of LCAs, full length subframes and a cage. And suspension, suspension, suspension. For drag I'd do the UPR front K/coilover setup and a good set of drag springs/shocks out back, for corner carving you've got really only Max Motorsports as the single quality "budget" option for going around turns like a boss, then to get crazier you look at A47/Griggs. You'll also need to upgrade your trans to a 26 spline input shaft, upgrade the forks and get a really strong clutch. Or just go auto which is what 9/10 cars making that sort of power wind up doing, at least for straight line racing.
So that's it in a nutshell, not cheap and the motor is just a single piece of a greater whole. You can have all the power in the world but without getting it to the ground you'll have a dyno queen and that's it. Case in point, the numerous GT500 owners out there making 800+ to the wheels on mostly stock suspension and they wonder why they can't even run a 10 second 1/4 when the dude in the ported Eaton Termi with the auto/solid rear swap and setup for drag is running 9s.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.