Wouldn't you want your sail to still go to the top of the mast?  Of course the foot is shorter and it is cut flatter but I don't get it.  Any other boat I have seen all headsails go to the top of the mast.  I have a headsail that came with the boat it has a tack pendant but it still wont go to top of mast, it looks about 6 feet short.  I assume it is not a catalina 36 tall rig sail but it works ok.
So I was looking to get a new headsail and in the owners manual they list for a tall rig 

110 luff =41.5
155 luff= 47
I=46.75

Is it because the jib track won't work with a 110 that goes all the way to top of mast?