Are you of the mindset to pay down the loan to increase monthly cash flow, sell for the capital or refinance? 

I would recommend looking into West Kensington, Frankford, and Port Richmond-  You can still find great deals there withe excellent cashflow, and I believe the path of progress will continue to march into those areas and increase values. 

The reason I estimate $120k in repairs is because I want to increase the ARV and increase rents, which brings me to my next point:A 4-unit renovated comp with the exact same specs showed up on the MLS today for ~$1,600,000!

This is the information I found in the city's website:"Will my property taxes increase if I build an ADU? 

You can then increase the value using your rehab/renovation skills and potentially refinance once the property is stabilized. 

Hi BP,Recently I have increased my net worth (through my equity position on a property).

It's somewhat surprising as prices for Mass overall continue on their tear as "last month the median single-family sale price increased 5.8 percent to $402,000, up from $380,000 a year earlier.

I am currently doing as much research as possible on the side to increase my knowledge in both investing and developing real estate.

Also i hope the property does increase in value. 

The increased interest would be negligible- a point at most.