You're on the right track. I used to work at JDM Engineering in NJ, and as much as I am critical about some of their business practices, they are no doubt the best in the area for the 3V Saleen cars, practically had a factory backed program. The tune will make a huge difference in the drive by wire. Keep in mind you may need 60's on smaller than the 3.4. I think you'll be really happy with those upgrades without breaking the bank and can spend otherwise on appearance/suspension, etc. People who tend to go farther than that in my experience are on a slippery slope to eventually a built motor, fuel system, and twin screw.
It was unpopular at the time, but I'd really recommend a 10% or 15% over doing the 3.4. It's expensive, but creates a lot of torque and helps a ton with the belt slip issues. A thump_RR tensioner is also an expensive, but effective, upgrade. Skip the braces and grinding the tab off the stock tensioner and all that crap.
About those wheels?