I need more timing adjustment

Did not install new dist,everything is stock,been in storage shed for 15 yrs,prior to that,daily driver. Let me ask ya, have a good Carter 1 barrel on her now,what about trying a Holley 1920 on her???? We are gonna put electronic ignition on her this weekend,but can get a reman 1920 from Orielly's. Which is better,Carter or Holley?????Right now the gas mileage is 19.8,but it flutters shifting thru gears,not as smooth as I want it,yea I'm anal. Going with pertronix 1361a ignition kit,this is gonna be my wife's daily driver,she drove it to work today. I just wanna tweak it to the max and cover all the bases Thanks again