Long reply coming :Not trying to thread crap, but when you first started talking about buying the SS, etc... everyone was like why not just throw a SC on your mustang and a FRRP handling pack & call it a day. It would give you 90% of the bang for 90% less buck. And then you wouldn't mind driving your car as its just a $40k car + $10k in upgrades max. Oh well, this will be interesting to see.
I bought the SS for two reasons...1) I didn't have the time to build it, 2) It's pretty cool owning a Shelby SS that is also a 50th Anniversary car (so I have to admit I do like showing it off and getting my ego stroked a bit...who wouldn't). I didn't (and still don't) have the time to build the car in any reasonable period of time. I bought the second car about 1.5 months ago and have only had the time to go to the drags twice. I haven't had anytime to do any mods. Yet, during that same time I've put 1500 miles on the Shelby including dragging it, going to a forum rally, and showing it at a car show. I did finally put the shift light in it and I'm buying a set of drag radials/tires. Second reason was the cool factor. I've been called out by a bunch of Hellcats and am going to drag it again in a little over a week. I am making a bunch of new acquaintances because of what the car is.
I expect the Clone will be finished some time by the end of the summer 2017. Hopefully, by the end of this summer I will have the gears, driveshaft/half shafts, wrinkle slicks, and shift light in the Clone. That will hopefully allow me to move the car towards 13 seconds (obviously the gears and tires are improving the time, and the rest supports that).
So, if I didn't have the Shelby I wouldn't be having anywhere near the fun I've had so far this summer and will have. Finally, that Clone is going to cost slightly over $60,000 when it's done. The SC alone is $9,500. IMHO installing just a SC and Ford Racing suspension package would have created problems for me (this is my opinion...not knocking people that have done what you suggested). I would have been breaking drivetrain parts, wouldn't be hooking up, could possibly have cooling issues, and may not have had enough fuel delivery. So, driveshafts, half shafts, rims/drag tires, cooling fans/radiator, and new fuel injectors would have to be part of the build. That's a lot of money, and there's a spreadsheet at the beginning of this post detailing those costs.
I realize what I'm doing is over the top. I likely won't own both of these cars in 10 years. One will have been sold. If the Shelby goes up in price, then it'll be sold (I do have the lowest Shelby CSM # 50 Anniversary numbered car and that may be worth a premium to the right buyer if they want that combination of SS and 50th anniversary car). If it doesn't go up then I'll realize it's not such a special car and then I'll sell the clone and drive the Shelby a lot more (probably take a bath but have had a lot of fun with it and made some awesome memories).