Good luck with the build! Theres alot to do and even more to learn! Coming from a guy who just finished his install on Toms Kit.
For 350whp... you need:
2.LSD (optional, but HIGHLY reccomended)
5.Stronger Engine Mounts
You should also consider new suspension, timing belt, water pump, and other such things. All said and done, expect to spend over $7,000 on a build like this.