Would 100% raise a red flag, 90/10, 80/20?

A bit risky, but it worked.Having said all the above, I did not have the complication of a mortgage on these properties because I used line of credit funding on my principle residence.  

There's extra capital needed to remodel the 3-5th floors, but I don't know what kind of options there are for funding that.The area is on the border between downtown and a less friendly neighborhood, but the city just got a big government agency to move in about a year or two ago.

And after 30 years of a $1.1M paid-off house appreciating in an up and coming town, when I decide to downsize at the age of 65 i'll fund a good chunk of my retirement, or hand off a nice asset to my kids.If you could hypothetically take $100,000 on a HELOC and turn it into $5,000 per month cash flow would you do that?

If it is a specific list of home owners within an area(s), then I would rather create a personalized postcard campaign raising their pain points and you providing them benefits and credibility so prospect will call you.  

If you don't have the funds to advertise it will be more difficult but no immpossible.

I don't know if you're aware but this building is under rent control and the 2nd unit's $1,900 rent cannot be raised much and there are tight restrictions on removing the tenant.The type of buyers this property is perfect for are two separate parties (think friends or siblings) buying it as a TIC with each party occupying one unit.  

After a months work to raise the rent, change the Home Owners Insurance company, get an Appraisal and maybe pay down a little on the mortgage to remove the Mortgage Insurance, I should be able to show up to $300 a month Net Rent.

Then I can fill a couple spots at the higher rent and in a year raise rents on everyone else. 

Use a transactional lender to fund the deal.