I also went through some timeslips posted on the 2018 race and out of 4 cars and 5 slips the conversion chart listed above was more or less .2 faster on 3 of the 4 cars in the 1/4 mile. 1 was dead on.
So use it as is with the 1.56 conversion factor or use the 1.5835 conversion factor that goes with the majority of the cars?
just remember, the tables NHRA or anyone else would create would be for Drag cars. Not street cars. It's like dividing 1320/mph, much easier to get on a drag car than a street car because of the gears/converter/weight being used.