340 or 360?

My Duster ran 13.9's with a LA 360, stock 360 heads, dished pistons, stock exhaust manifolds, stock auto and converter, and 2.45 gears. Cam was basically a replacement 360 4bbl cam (.427/204@050 on the intake). It did have a 750 DP on a dual plane intake, though. I wonder how much quicker I could have ran with a stock 340 ? Means they only ran 14's with 3.55's, do you think the 2.45's would have helped the 340 move my Duster past 13.9's ? :realcrazy: