switch from 4 to 8?
 

I'm scoping out a 91 LX, but it's a 4 cylinder. I don't really want a four cylinder because I've had to deal with a 67 with a straight 6 for four years and I hate how it can't hardly get down the road. On to the question: would it be possible to buy this LX and switch the four for a 5.0? The car currently has a five-speed, but that could be changed too. Would I have to change out the entire suspension? And what about the gears? I'm completely lost on this one, I need some serious help!

If you buy a 2.3L, to get it to performance/handling levels, you'd basically need a 5.0L donor car. To name a FEW things you'd have to swap over for a good daily drivable mustang you'd have to get (because basically the 2.3L drives like a RWD tempo):
2 core radiator, springs, struts, shocks, sway bars, spindles and brake assemblies, master cylinder, rear axle and lines, exhaust for the V8, motor mounts, transmission (the 4 cylinder T5 has a very low torque rating and will break easily to abuse), quad shocks and brackets, new instrument cluster (the 4 cylinder tachometer won't work with a V8) or a seperate tachometer, i think the driveshaft may work for a V8 swap (not sure if there's a length differance).
Basically it's not worth converting unless you can get parts for free or cheap, plus it's ALOT of work. It's almost always cheaper just to buy a 5.0L, not only that but a factory 5.0L out-corners, brakes and accelerates a 2.3L by far. Having driven both, the 2.3L feels like a COMPLETELY DIFFERNT car than a 5.0L. It sways, dives on braking and wheezes it's way slowly accelerating. It's worth your time to save up or find a good deal on a 5.0L to begin with. Good luck!

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'84 Mustang 5.0 LX
My car