Balloon in 84 months: which yield number are you actually pricing to?

Note on my desk, 9% coupon, amortizing on a 30 year schedule, balloon at month 84. Balance 118k, seasoning is 29 payments clean, I'm being quoted 74.

At 74 the yield to the balloon is a big number because I get a slug of principal back in year seven. If instead the borrower refinances at month 30, the discount accretes over two and a half years and the yield is bigger still. If the borrower can't refinance at the balloon and I end up extending or modifying, my money sits at the 9% coupon on a much larger basis and the whole thing turns into a mid single digit hold.

So there are at least three defensible numbers and they're far apart. I've seen people price to maturity because it's the contractual case, price to an assumed prepayment because that's what usually happens, and price to the extension case because that's the one that hurts.

My problem is that the choice of metric is doing more work than the diligence. Pick the prepay case and 74 looks generous. Pick the extension case and 74 is roughly fair. Nothing about the borrower's file tells me which one happens, and the borrower's ability to refinance in 2032 is not something in the pay history.

Which number governs your bid on balloon paper.