If *I* were you I would purchase a fuel injection system from CUSTOMEFIS (www.customefis.com) I have searched the 'net high and low for fuel injection information and this guy really knows his stuff... He builds both TBI and multi-point systems using GM components and computers for INCREDIBLE prices. His kits are worth it just for the parts. Performance-wise a fuel injection system built with factory components (possibly with bigger injectors) and properly tuned can handle all but the most fire breathing motors, plus you can walk into any parts store in the country and get a fuel injector/O2 sensor/MAP sensor etc... try that with a holley or edelbrock kit...
The advantages of big-name aftermarket kits are "seat of the pants" tuneability, you can twist the knob and FEEL your car surge with more power... while belching black smoke from running too rich. If youre really interested in reaping the benefits of fuel injection, a system built on a GM (or ford) computer can really out-perform most aftermarket kits because its DESIGNED to get the most power AND the best economy so GM can sell more cars. Plus, with a CSB most parts literally bolt right on...
There are OTHER people out there also building fuel injection kits from GM parts, Bill Howell was GM fuel injection engineer who now builds kits, though he seems more off-road oriented (www.howell-efi.com). I havent purchased a full kit from CUSTOMEFI'S but he has modified my ECU to take a flash chip (well worth it) and we're currently working on a custom system for an air-cooled VW so I would definitely reccomend him...

Bruce
1981 242 w/ GM TBI 350 and borg warner T56 six speed (but no limited-slip rearend yet, grrr)