[MKS427]

If you want an aluminium body, I would look at Kirkham. I seen a few and they look great.
I recently built a Factory Five MK IV and it went well. My only experience building a kit. I can tell you it handles great and has no bumpsteer. I went with the 17" wheels and Wilwood brakes, so it stops great too. I did end up upgrading the cooling system as it was inadequate when stuck idling. A better fan and a proper shroud may have corrected the problem, but you know how it goes. lol
It really has a lot to do with budget and what you want from it. Period correct show piece or a car you can take to the race track without regrets. If the latter Factory Five Racing has engineered theirs for the track. The 3-link works great, in fact one of their techs recommended it for racing. However, this was just prior to them setting up for the new Mustang IRS. If you are going racing, you might want to consider power steering.
Good luck,
Mark