personally a 4-8oz.
smutts on a light rod is normally a bad idea, seen a few smashed and people spooled.
cod like BIG baits so having the heavier rod will help with the casting.
depending on where you are fishing 4 oz's might not be enough to hold bottom, and although you could cast a heavier weight you might not get it as far.
4-8oz dosnt mean its going to be a broom handle though, ive seen some that arent much heavier then a 3lb carp rod.