Subdivide property before you sale? Or is it better to sale your home as one?

Here's the thing.... I have two house that are right next to eachother. One house in on 1/4 of an acre and the larger house is on 1/3 of an acre. I'm selling both of the homes and have 60 days to do so because I'm on a contingent offer with a new home that I am buying. It's a very good size lot that both of these houses are on for the area we are in. Everyone keeps telling me to see if I can subdivide my larger lot to make more of a profit. I've contacted the city about this and they told me that each lot has to be 8500sf and that it would not be possible. After that I started looking at brand new homes that were being built in the same town and I see lots as small as 6000sf!!! So why are they telling me I cant? If it is possible would it be wise to get it subdivided before I sell and sell that lot seperate? Or would it be better to sell the house on a 1/3 of an acre as is, having the buyer relize the lot would be subdividable.