Back it the 80's when i worked at a full service gas station (remember those?) a gal with a new Jag pulls in and asked me to put in some Power Steering fluid. I started to do so and she jumps out and tells me I am putting it in the wrong place! I was a little stunned and I showed her the "Power Steering" molded into the cap. She pointed to the master cylinder and told me her husband said it goes there.
He didn't! He did! Crap. Lady, are your brakes acting funny? Yes. OK, your brake system is toast. Park it over there and call for a ride. I'll bet your glad it was him instead of you.
Just so this isn't a highjack, if you removed the fluid before pushing the brake pedal, your fine. If you have 4 wheel ABS, you may need to go to the Chevy dealer to do a computer reset for your ABS and then re-bleed. Some do, some don't. Check a Hanes manual.