Your options are limited.
1) Jumbo financing: 4.5-4.25 best case scenario with fees.
2) FHA 15 year fixed financing, providing you've got 22% equity: 3.5% or lower. Why 22% equity? You avoid MI.
3) $625,500 1st TD - 4.125% or so, with a 2nd TD, providing you've got 80% equity for the most part. Some will go higher on the Combined Loan To Value.
Kinecta FCU has a 1st/2nd combo loan that's pretty aggressive. We don't offer the product, but quite a few mortgage bankers do. New American Funding is one, or just go direct to the credit union to get the loan. I can refer you to someone at NAF if preferred. PM for details.
My .02c
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