If you want a 12 second car, or even a high 11 second car, the 4.0 six banger is fine with FI. If you want to go way beyond that, you are going to need some cash. I had a fully built setup and threw a rod. I had pistons, crank, heads, cams, fasteners, bearings, everything minus the rods. I had the stock forged rods. So budget some cash to get some rods...and good luck if you go with moronas rods, it takes him at least a year to do anything. The SSM rods are good, but they stretch over time, so that left me with custom rods costing 2-3k.
It's a stout motor, and can deliver power, but I wanted a 10 second car that can touch 9's when I want to. So I went with a 5.4 3v truck motor, and it was actually cheaper this route as I was able to use mod motor parts off the shelf. I got another 5.4 3v block, with forged internals going into the car late may early june. Then I can up the boost to 17psi.
If you go with a 4.0 V6, I would cut to the chase and go with a PH turbo.