yes, you could use the HELOC as a down payment on a hard money loan, and then the hard money loan for the rest.  

Are there specific lenders or servicers that are more likely to call these loans?

Loan is just over $108k. 

If you are going to be an owner-occupant, want a low down payment, and are planning to do a renovation, the FHA 203k and Fannie May Homestyle loans are your best optionsHow do you know the property is currently upside down on the mortgage? 

You could get a loan from a local bank or private lender to fund it

I know that interest on the acquisition loan can be included in the cost basis since it’s inventory.

This term replaced "subprime" and looks a lot different than subprime loans of the past.

To qualify for a loan, focus on having a credit score of at least 620 (or 580 for FHA loans), keeping your total monthly debt under 43% of your income, and saving enough for a down payment and closing costs—about 5-10% of the home's price in total.

Most 1-4 unit real estate investors are using DSCR loans right now for any buy and holds while flippers lean on higher leverage bridge/fix and flip loan options with higher interest rates.

I argue that more money in the hands of the rehabber makes the loan safer.