Zoning Question - Austin, TX (SF-3 --> MF-4 possible?

[Brian Marver]

I'm looking at a property in Clarksville area of Austin, TX that is zoned as SF-3-HD-NP. It was listed on MLS as a Triplex that is zoned MF-4, but through discussions with existing tenant (who looked at buying in past) it has been uncovered it is actually zoned SF-3-HD-NP (Historic District; Neighborhood Planning Oddly enough the TCAD shows it as MF-4 but we now have confirmation it is not per the listing agent.

The lot is 6000 SF, all of the other lots on the street are MF-4.  Does anyone have an idea of what it would take to get it re-zoned to MF-4 given the context or is that highly unlikely.