Getting the engine in is a bit tricky. It's huge.
The kit car
oil pan is a T design. The motor mounts are not the best design. They end up fitting between the
oil pan sump and rail. You'll have to remove the
oil pan to get the engine in.
https://www.cantonracingproducts.com...rear-sump-pan/
As said, the engine is really wide. You'll need to remove the valve covers to fit through the hood opening.
And the steering may interfere with the valve cover just a tad. You might need to clearance the left front corner just a smidgen.
The stock alternator is much too big to fit in the stock location; it hits the frame rail. You'll need to adapt an aftermarket racing 80A alternator. You'll have to custom fabricate a new mount, and add an additional idler pulley.
Mini Racing Alternator - Performance Distributors
If you don't ever plan on installing a blower, the Power by the Hour has a bracket set to move the alternator to the right side of the engine.
https://pbhperformance.com/product/s...a-5-0l-coyote/
If you're thinking about power steering, that can be a challenge as well because the Mustang uses electric steering. There are a couple of companies that make brackets for this. Most of the hydraulic pumps fit on the right front of the engine; the same place the PBTH alternator mount sits. Since you won't be installing AC, you could fabricate a mount there to install a KRC pump with remote reservoir. I'm seriously considering electric PS.
The aftermarket alternator works just fine. At idle with all the lights on, the alternator makes 28A (I measured it). The stock alternator is rated at 120A or so. But it has to run a LOT of electrical accessories on the Mustang.
Adapting the factory wiring harness is a nightmare. There are so many bundles of wires that you just don't know where to start. Power By the Hour can help with some harnesses. But it's not a simple Power and ground connection. You could buy the Control Pack from Ford For $2,000 and simply replace all the original wiring harnesses.
The factory computer is mounted to the right front corner of the Mustang engine bay. It doesn't really fit anywhere in the BDR. You'll need to open the harness and move the wires around to make it fit the way you want it to.
You can use the stock factory computer. There are ways to eliminate the PATS. And it can be tuned. Getting a custom tune on the dyno is a good idea if you've made significant changes - intake, cams, blower, etc. Otherwise, the stock tune will probably be just fine.
The tachometer only runs at half speed. Even after installing the adapter from AutoMeter, it still only runs at half speed. I plan to replace all of the gauges this winter or next. I'm not that concerned about it right now; I know how to read it.
If wired correctly, you can use the push button in the dash. It's nice, and kinda cool, but I don't see that as a big deal.