In 09 I drove my 69 Sat from Houston to Detroit and back for Woodward. It has a 528 Hemi/TF/3.54 Dana. Then, it had the MP crossram, twin Holley 770's and a 266@50/650 solid cam. Running 65 all the way up and back with the A/C on, it got between 8-11 mpg. With a Dynamic 3600 stall converter, I always wondered how much a tighter converter would have helped.