Significant property value increase, Expecting 15K windfall

[Jack Lane]

This is my first post. Thanks for your comments, 

I bought my first house 3 years ago for 95K, I've put an additional 20K in renovations and I get 1.4K per month in rent. I estimate it's current value to be about 150K. I have amazing unicorn renters. They pay ahead of time, treat the property great and they plan to be around  a long time. I will very soon be the recipient of a small windfall (probably about 15-20K). I spoke with the city recently and my lot is eligible to be subdivided into two city lots, which I am considering. The process will cost up to $2500, but will raise the value of the combined properties to at least $175K.  The downside is a likely modest increase in property taxes. 

We plan to use the windfall to pay for the subdivision, a modest about of improvements, and pay down the renovation note. When this is all done (in 6 months), I conservatively estimate that we will be in at least a 60K positive equity position. 

My question is should I cash out and get a 4-plex on an FHA? Or should I ride this ou until I pay it off?