I have an 89 350 TPI with the 700r4 overdrive transmission. I also have the 9 bolt rear with 3.27 gears.

If I install the 3.73 gears what should I expect? Good or bad?

 

I'm a non-computer guy, so with the disclaimer that"I don't know how it will effect the computer" I would say yes, absolutely. Generally speaking the most bang for the buck in getting a car to accelerate is by changing the rearend gearing. (just like , generelly, the biggest bang for the buck to increase engine output is a set of headers). I have been running 4.11's in my 83 L69 and they're a little steep, so I went back to the 3.73's. They're a real good all around ratio IMO. I would also recomend these guys:
http://www.reiderracing.com/
I have had nothing but good results from them, BTW, if you're gonna pull the rearend apart, you might as well put a posi in it, or you'll be sorry later.
Here's what a 4.11 sounds like (using 1st and second gear in the vid)http://www.fl-thirdgen.org/blacksheep-1/camaro.mov