Unfortunately, there isnt any way to know what amount of the refund will be applied against the debt and what amount of the refund will be given to you.
When you complete the injured spouse form, there is a worksheet that allows you to allocate income, expenses, deductions, and credits between you and your spouse. The IRS uses this allocation information to determine how much of the joint tax refund will be applied against the debt and how much will be given to the injured spouse. However, the IRS does not publish how they make this determination.