If you decide to further pursue this one you need a local structural engineer who can assess the already completed fix.

Declining local economies invariably hurt home values.

Utilities, taxes (property, local vacation, & income), landscaping, furnishing / decorations / amenities, pest control, & supplies (soap, TP, etc) are the big ones on my STR calculator that you didn't mention.I'd also recommend using the enemy method to determine expected income.

Our locals will negotiate on sight distance but there has to be a reason.  

Ask local property management companies what they are seeing for utilities for similar fourplexes.I don't know the age of this building but mine are 80s built.

I recommend looking at B neighborhoods up in your local metro.

Partner with a local lender.

That 4-plex already has a local realtor.

I was just at a capital raising event in New York City pitching miami and columbus. by far there is more interest in miami for development, land entitlement, etc. you also aren't local so I'd discount what you say by like 80%. even if you are looking at "condo" investments, that's about the poorest way to invest in real estate so I'd say just you looking at that says something about your experience level. 

Do you have a floor & Decor location there locally ?