Newbie Question: keep duplex or turn into a 4-plex?

[Tess Tari]

Hi All! I am a newbie here and have an interesting situation.

Short version : Should I turn my duplex into a 4-plex?

Long version : I have a lot of history with this house.  I lived on one side of the duplex, as a renter, for 14 years before I finally purchased it.  I have seen a few tenants come and go.  This house is zoned for a 4 plex, but the previous owner was not interested in capitalizing, so he turned it back into a duplex.

When I first moved in, the south unit was two separate 2/1 apartments with the upstairs tenants having control of the 1 car garage; they shared the yard and the laundry room.  My side was a 2/1 upstairs with an unfinished basement. It was owned by someone else.  It was purchased 1 1/2 years after I moved in and that owner turned the two south units into a 4/2.  

We are currently in the process of beginning to finish our basement and bring it up to code as a possible rent-able unit.

The question is, should we turn it back into a 4-plex? The tenants previous to this had at least 11 people living in the 4/2 and the current family is 8, sometimes 9 or 10.  I am very tired of the extra large families living in this unit, and am concerned that it will be an ongoing problem, with a large unit.  3/2 and 4/2 in our area with similar square footage are going for $1850 - 2500. If we turn it into two units, we could easily get $1000 - 1300 for each unit.  They would have to split utilities unless we come up with another plan.

The "big but" is that the previous owner pulled out the downstairs kitchen.  

I would love to hear thoughts, ideas and feedback.  I have some time, as it is currently rented.