Hmmm...the original guy seems to have a fairly long and broad, but pointy chin combined with a short forehead. First, you could try moving up your sim's nose, orbits and mouth for a few clicks and then reducing the "squareness" of his jaw, giving it a more triangular shape. Increase the chin's width and length, then use the other chin button for making it more pointy.
(know which buttons I mean? The one for broadness says something like:
|__| -->
|_____|
while the shape slider has this icon:
U -->
V
...or something similar
)
Benvolio's mouth is extremely wide. The lip shape of your sim is already very much like his, but you definitely need to widen the mouth. The lower lip could be a tad more |_____| - ish (yep, I mean the opposite of V- shaped :D). And, according to
this photo, his upper lip is really pouty in comparison to the lower.
You're right about the nose, too; the nostrils are too narrow yet. Also the transition between nostrils and bridge should be less smooth. This could be fixed by using the "general nose width" slider a little; after this, make the nostrils a lot wider. Then, move up the whole nose and the tip down seperately. From side view, his nose appears to be quite flat with a slightly convex shape - maybe make the whole nose point up and then the tip down.
Finding the right shape of his eyes is difficult due to his frowning. From what I can see on the two reference pics, they're almond shaped and squint with the eyelids barely visible. There's no noticeable curve on the outer parts of his upper lid, it's almost completely straight while your sim's eyes are quite round - I'd say move the outer eye corners up and then make the eyes slant downwards a little.
On the skintone: This one looks too tanned IMHO, you need a more rosy-pale tone. The lip texture on this one is very convenient for your sim, though, so perhaps apply a reddish facemask with huuuge pores. A bit of stubble would be good, too.