Find a complete wrecked truck, TBI F-body, or B-body and steal the complete computer, EPROM, wiring harness, EVERYTHING you can get your hands on, because it'll make the whole process easier. My uncle and I did the swap on a '69 C-10. We integraged the '69 wiring harness with the TBI wiring harness. I ended up swapping out the EFI because it never quite worked right. I'm confident that it was something in the wiring. In retrospect, the best bet would be to use a specially made wiring harness from Street and Performance, Painless Wiring, Ron Francis Wire Works, etc. You're looking to spend about $500-$600 on a harness, but it's probably the best bet, since many of the sensors send the ECU signals in millevolts, and if you have too many, or bad splices in the system, the ECU will get bad readings.
Some other things to think about.
* You will more than likely need a VSS (Vehicle Speed Sensor) I picked mine up from Street and Performance, and it's totally trick. It's got a pulse generator built in for the computer, and also has a speedo cable output for older trucks. Plus, it's bitchin' looking, being as it's blue anodized billet.
*Fuel pump - An auto parts store piston type in-line pump will be fine. They will easily put out the 15 or so PSI that the TBI requires, and flows plenty to keep it fed.
That's all for now, but just ask if you have any other questions.