Depends on crime rate along with a lot of other factors but at the end of the day, how much headache do you want for a potentially higher return.

Because it’s our personal home, where we will retire in 20 years and die in 40+, the cost to build it is almost not a factor since we will never see it sold.

Does this factor you living in one unit?

If you ran the numbers and factored in expenses it's a no brainer.

As you explore these types of deals, part of your due diligence should be to research the local building departments to ensure the time and costs associated with re-zoning and re-entitiling the property are properly factored into your underwriting.  

How to factor in the age of the property, because older properties require more maintenance.2.

In addition, ask about important factors like pets, children, smoking, and criminal history

Property details:1905 E Adams Ave, Orange, CA 92867Purchase price is $839,500 - Regular 20% down over 30 years 5% interestAVG closing cost $5,000ARV $839,500Repair cost 50,000 - Property looks in decent condition but i just wanted to factor in some repair cost plus Yard need TLC. 

Currently a crappy sports bar with no cool factor at all which has been operating miserably out of this space for as long as I can remember.

I would suggest "running the numbers" and look at your cash flow after factoring in your mortgage, CapEx, taxes, etc.Jacob