Final Challenge:
74 < 81
53 < 62
will give you 127, the highest possible score.
Place the highest digit in the tens column on the right hand side and the next highest digit in the tens column on the left hand side. With the remaining numbers, do the same for the tens columns in the second row.
For the ones columns, start with highest two digits of the remaining digits and place them on the left hand side (any row is fine) and place the remaining on the right hand side.
Another way to look at it is that the difference between the numbers on left hand side and right hand side using those digits should be the smallest to give you highest possible score on the left hand side.