What gear?

Ok since I found out today that I currently have a 3.55 gear and not the 3.91 I thought I had.. Help me out. My car is a 1970 duster. Full interior so probably around 3200lbs. 360 284/484 mopar cam. 750 holley. 727 with 3500 stall. Had it at the track 3 weeks ago ran a best of 8.23 I think. Never used 3rd gear shifting at 5800rpm. Was running out of fuel in second about 5300. I fixed the fuel problem and ran a 8.15 last week. Still didn't use 3rd gear. Thought I had a 3.91 gear but turned out to be a 3.55. How much would a gear help me out on times? I'm running a 28" tall tire. What gear should I run. It will only be for the track every now and then. Otherwise it'll have the 3.55 in it. Any help is appreciated and if you need any more info let me know. I have access to a 4.30 and a 4.56, but if it really isn't going to help much then I'll leave the 3.55 in it. I really like the 3.55 on the highway it cruises nice at 70mph.