Size 0 top, Size 12 skirt.

Modifications:
Sleeves - on row 5, increased 10 st evenly (because after knitting as written, they cut off circulation to my arms). BO after 8 rows instead of 10 (due to amount of yarn left of that colour)

Decreases to waist - decreased 4 times total every 12 rows to go from size 0 top to size 12 skirt.
Then knitted a further 30 rows to hit my waistline.

Skirt - knitted continuously in one piece from the top and worked top down.
Increased every 24 rows until I was at 450 stitches total.
Colourwork omitted.