-Want to install an 89 305 TPI engine and 5 speed manual transmission in my 57 chevy
-I initially intended to use original wiring harness from camaro
-Began to reconsider when installing steering column from camaro (I began to realize that when work on the car, I only get enough time to bolt things together rather that troubleshoot and match wires for the ignition switch, guages, turnsignals...etc, car ends up sitting for months, blah blah blah)
-Now considering purchasing a wiring harness from painless or competitor (I don't even know who thier competitors are, suggesstions anyone?)
-I am also considering purchasing a stainless steel steering column from flaming river
-I guess I want to try to make work what I have before I invest in these expensive parts but need to talk with others that have pursued similar projects to the one I am working on
-any help will be appreciated.  

your tpi will not work without the computer.  so you have to use it.  i doubt that you can buy a wiring harness after market for your gm tpi that will not require being wired into all the other ecm controlled functions.  you have only two choices:

(1)if you want the tpi then you have to use the computer...

or

(2) you don't use the computer and you ditch the entire tpi setup and put a carburater on the 305.  

Contact FAST (they're part of Comp Cams) they have controllers specifically for this kind of install. Another possibility is a Mega Squirt system.