The math indicates the HELOC would be the least expensive pay down method to achieve that *IF* all the necessary requirements were met.  

On an estopple the tenant indicates what they paid in deposits, current tenancy status, appliances owned, etc.

The very fact that they are undocumented indicates that they already broke the law.

Currently, Syracuse multi-family properties are yielding a 10 cap rate, indicating a strong investment opportunity, while in Binghamton, large multi-family listings average at or below a 7 cap rate.

There are key indicators outside of credit that will help you make a decision

@Farzan SetayeshNot a local investor, but here is a data driven look at the market conditions in McAllen TexasTwo of the most important market performance indicators, population and median home values, have been increasing steadily for the past decade   Rents have followed a similar trend The chart to the right shows median household incomes over time, which have also been increasing. 

Are you located in 96797 as indicated on your profile?

What key indicators would you recommend for identifying these promising neighborhoods?

Pay attention to the loan-to-value ratio; a lower ratio can reduce risk by indicating more borrower equity in the property.Building relationships with lenders is essential.

I do income potential reviews for clients all the time, every market has subtle differences but these are generally good indicators.