I say 1 build it you will notice a different approach every time you drive it you won't regret it keep the Z there's always head turners checking it out you don't always see a Z nice gettin complements as well
As for the mustang yea it's quick in a straight road but think of how many mustangs you see in a day v6 v8 turbo 4 Shelby etc vs a Z
In my area where I live I've only seen a total of 5 Z'S and city has a population of close to 30,000 people
In the end choose the best for you