The TPI swap is pretty straightforward but do your research first. There were some important differences between the different versions of TPI that GM put on Camaros, Firebirds, and Vettes, even within the same year. There are a bunch of great websites and a couple of books around that helped me a lot.
www.chevythunder.com
www.jagsthatrun.com
www.thirdgen.org
The best thing to do is to find a complete, running Z28 or TransAm. That way you can be sure that the TPI is working well and you'll have all the sensors, etc. needed to make it work. Try and get one with a 350, not a 305 like I did
since the injectors and sensors are different.
If you are getting a crate motor, get one with the newer style center bolt heads, it'll make the intake install easier since there are 2 different versions of the intake which differ in the angle of the 2 middle bolt holes on each side.
The most time consuming part for me was the plumbing. You need to put in an electric fuel pump and a new fuel lines. The stock supply line is too small and you need a return line. I also installed an intank pump with a built in baffle for more reliability. You'll also have to have a bung for the O2 sensor welded into your exhaust manifold. If you've got headers like I do, it goes after the collector and you need to use a heated O2 sensor which means a little extra wiring.
It's a fun upgrade to do but it isn't exactly a bolt on. I've kept the entire parts list from my install which might help.
Keep asking questions.