Yes, it's possible to get a DSCR loan on your rental property to pay off the outstanding HELOC balance ($285K) and the remaining $390K mortgage. Based on an estimated appraisal of $1.1 - $1.2 million, you could secure a loan of up to $900K (75% LTV). This would cover the $675K needed to pay off the existing HELOC and mortgage, leaving you with about $200K after payoffs and closing costs.
However, it's important to consider the cash flow impact. To qualify for a $900K DSCR loan, you would typically need to show rental income of around $8K per month, assuming property taxes are about $10K annually and insurance is around $3K. Given that your rental property currently cash flows over $3K/month, the DSCR might be too low to qualify for the full $900K loan, unless you can show additional rental income or strong reserves.
If your goal is to access that $200K for another investment, refinancing with a DSCR loan could be worth losing the low 2.99% rate, especially since it would eliminate the high-interest HELOC. However, you should weigh this against the potential for a higher DSCR loan rate, which might affect your overall cash flow. I'd be happy to help you run the numbers to see if it's the right move for you!