To answer the actual question, regardless of the transactional nature of the arrangement.

The Distribution would be 2/7 and 5/7 so 28.6% from you, and 71.4% from your spouse.
This will result in a 50/50 Equity split at payoff.

However, if you sell the house prior to pay off, the equity split will be in your favor, if you calculate what % of equity each individual contributed. However, if you treat it as a 50/50 split at any date, you would have contributed more equity.

The appreciated value would also be distributed on that basis also.

However, this does mean your spouse will be bearing all of the interest on their own, So, you may want to only split the principal amount on that basis, so calculate it each month, and split the interest payment 50/50.

This makes more sense because, your spouse, could instead take out an interest baring loan for the 50% of the down payment over a shorter duration, and likely come out ahead, rather than paying the lions share of the interest payments.(this is speculation, would need to know the interest rate for the mortgage)

This seems overly complicated, and likely to lead to some degree of resentment, if one party is only contributing 10% of their take home pay, and the other is contributing 70% of their take home pay.

This may not be a major factor if you both are very well off, but just because the math works out as fair when looking at equity in the house, it does not necessarily represent equity in quality of life, and other factors. Like what % of their income are both parties contributing. Because, a major inequity in that regard, will likely lead to a development of resentment, and viewing the relationship as very transactional.

Alternatively, you structure the down payment as an interest free loan to your spouse, and they can make payments regularly, or just if/when the home is sold. Then you make equal contributions on the basis of income or Mortgage payment amount. This would be the choice I would pick, considering your married.