Wow! You know what you are looking for... so first of all, congrats on doing your financial homework (you are in the minority of consumers of financial products, unfortunately).
What you are looking for is a pay option ARM. 1% - 2% percent on the Negative amortization payment is possible, but a fully indexed rate between 6% - 7% is not out there currently.
The only place that could possibly offer something like this is World Savings because they're a portfolio lender. I also know that Quicken Loans is pushing hard on Pay Option Arms these days as well.
If you want an introduction to pre-screened mortgage lenders, Bills.com makes it easy to compare mortgage offers and different loan types. Please visit the loan page and find a loan that meets your needs at:
Sounds like you are a pro, but to learn more about refinance loans, I encourage you to visit the Bills.com Home Refinance Information page at http://www.bills.com/home-refinance/
If you enter your contact information in the Bills.com Savings Center at the top of the page, we can have several pre-screened lenders contact you to discuss the refinance options available to you. I wish you the best of luck in finding a loan the meets your needs, and hope that the information I have provided helps you Find. Learn. Save.