To get a better 60ft I think you need a lower gear and or more stall.
My D50 weights the same as yours with a pump gas small block and my best 60 has been a 1.33. It is 1.34 most of the time. Mine is stock leaf springs and home made caltrak bars, 4.56 gears , 5400 8 in.PTC convertor and 315/60 M/T Drag Radials.

1.33 60 ft,6.21 at 110.59 in the 1/8, pump gas small block,2950lbs,drag radials,mufflers and driven to track ...