If you had $80,000 in a heloc, what would you do?

[Zack Wills]

I bought my parents house from them a while back for well under what it appraised for. The result, I now have a Heloc for a little over $80K. Since buying their place (they still live there) my wife and I have acquired a couple duplexes (we weren't married at the time so we both took advantage of FHA loans). We live in one and the other is rented and cash flows well enough.

Here is where I'm struggling.  I want a modest rental property portfolio as a retirement vessel for us as well as cashflow to insulate us from an economic downturn (job loss/injury/etc), and I'm wrestling with myself trying to find the best way to utilize this 80 grand I have access to.  What would you do?  What strategy best suits you?

A little about me, Im a Realtor and I have a high paying W2 job at which I'm currently working a ton of overtime to pay down debt.  I have a partner who's willing to work with me (he's a broker who'm I have my license under), we've done 1 flip together at which we took a minimal loss.  He's since gone gangbusters and is tearing it up in our area of Tampa Bay/Clearwater flipping homes, though I don't know if that suits me as I already have a full time job that I work a lot at and don't want another.  

So what would you do if you had access to 80K?  Maybe I can learn something from yall's perspective.

Thanks all, and happy hunting