Most banks will look at the properties books and determine if its profitable.  

Many of the landlords in Worcester go for Section 8 rents as they are more stable, but then you are subject to inspectors determining if your house qualifies for their programs. 

Does anyone have any suggestions on how to determine a 'best guess' on approximate STR gross income?

The challenge is determining what leverage suits one's risk tolerance and market dynamics.

What's typical for a full 203k is that a HUD consultant will survey the property to determine what repairs are required to bring it up to FHA standards, then you come up with your "wish list" of additional work you want done, you get a proposal from a general contractor for all the work, then the lender will have an appraiser determine what the ARV of the house will be.

I'm looking at an 8-unit building and need help determining what price would make this a good deal.

I found that the property was once 4 separate units but recently renovated and is now 2 units with a semi finished basement.Potential Problem: I closed a few weeks ago and today I visited the City to determine what I would need to make the basement a legal unit.

@David Acosta...I understand it has to do with a determination in November that the region was a flood risk.

Next question is what will it coat to rehab the house so it will sell for the determined ARV?

One of the stats HA uses to determine your ranking is conversion, which would be negatively affected if you deal directly after a guest makes an inquiry.