1" bars are still undersize with a 440, especially it its still all iron (ie, doesn't have aluminum heads, etc)
I had 1" Just Suspension bars in my Duster which is a 340/4 speed, manual steering, no AC, manual brakes car with headers- or in other words, pretty light for a '74 A body. I thought they way too soft even in my fairly light small block car. Better than anything stock, absolutely, but nowhere near a performance handling torsion bar. They still left quite a bit of body roll, and the ride was practically plush. I have 1.12" Firm Feel bars in my car now, and I think it rides and handles great. I do run the Hotchkis non-adjustable Fox shocks, and I'd say Bilstein RCD's or Fox's are the only way to go once you start going much over 1" for a torsion bar.
I think a big block A body calls for at least 1.03" bars. And really, if you want it to handle well, I don't think you should go smaller than 1.06".