Knitting World Cup

I am knitting my husband a sweater. Noro Kureyon, colour 51 top down on circulars. One month to get it done, because I have selected it as my World Cup project. I don't think he realizes the sacrifice I am making by a) not diving into my first pair of socks, and b) working with slightly scratchy wool in the warm weather. I was able to swatch for it today, and am mildly peeved that the yarn shop owner I bought the pattern at convinced me that Kureyon was appropriate for this sweater. This one called for "light worsted", and there was another pattern I was considering which called for "heavy worsted". Never having used the Kureyon, I believed her when she siad this pattern would work better. It calls for US 6/4 needles at 20 stitches/4 inches. Using US 7 needles (because if that worked, I could use my Debbie needles for the whole thing), I got 16 stitches/4 inches. I gave it a try on the US 5 needles (thinking that this would justify me buying US 3 Addis), but the knit was so thick that I think the sweater would stand up by itself. I do have to say that I like the way that the colours emerge. Since it is a fairly simple pattern, I am going to proceed with it, but reduce the stitch counts by 20% (woo hoo, 20% faster to knit!). Now I have to figure out what size to make it. I am thinking the 50 inch manly size (hubby thought that the guy modelling the sweater on the pattern looked quite wimpy).