The ideal situation will do it as homeowner builder instead of getting a contractor. 

Ideally, the Post Office keeps leasing it as a Post Office. 

The main factor for me, if I try to correct the tax records, it might end up getting into higher tax bracket  and it may not be attractive investment anymore, but the big question I have is, will the city/county put it into higher tax bracket if we increase number of rooms and dont have to increase sq ft size at the tax records?

Great Boston is still ideal from the distance point of view, but the inventory is almost nil, crazy-priced and mostly antic.Deliver at least 5% ROI yearly after all expenses (taxes, management, insurance etc.)

Ideally, in a BRRRR strategy, goal is pull as much cash out as possible, or even have no cash invested at all after the refi, but since this deal may require keeping some of my capital engaged, not a perfect BRRRR strategy, but still offers a good ROI from an "equity gain" perspective and also from a cash-on-cash flow perspective ($350+ per month).

this is the ideal scebario as you can now renovate and put in a good tenant at market rate. inherited tenants are usually paying below market and not screened to your standards

I know this is probably dictated by many factors and local economics, I would just like to have an idea of what others may practice. 

Or your rents are too low, or the condition of the property, or a combination of many factors.

For mainstay American home prices, it will be a non-factor for many years to come.

(A) An owner is not required to disclose the fact or suspicion that a property may be or is psychologically affected, as described in subsection (B).