I used to drive a 78 Malibu with a million mile 400 small block while I was stationed in Canada. Had a 600 Holley crap carb and never had choked hooked up. It got to 40 below couple times, regularly below 0 most of the winter. Only time car didnt' start was when I had 20/50 oil in it. Put a pan heater on it, started right up. After regular oil in it, it never not started. I'd say tune what you have...I've been to Louisiana, it doesn't get that cold.