Instead of looking at the numbers of the pattern, maybe you should only look at where those decreases occur. If you decreased a certain way--every row at the neck edge for the front, then you need to do the same for the back.
Shape Armholes: Cast off 4 sts beginning next 2 rows. (66 sts on needle). Continue eve until bodice measures 4 1/4 inches ending with purl row
Cast off 4 stitches at the outer edges for the armholes on the back, regardless of the number of stitches left.
Working on these 22 sts continue in stocking st, dec 1 st at nech edge every row to 18 sts on needle
You decreased 4 stitches on the front for the neck edges, ,so do the same at the back.