Not being a credit counselor or a financial advisor (a fact that has been drummed painfully into me since answering on this particular part of the forum), I believe they will always take the higher score of the spouses. Your wife's score is not a terribly bad score. I believe it falls in the 65-70% category. That is to say her score is better than 70% of Americans whose credit histories are reported to the three bureaus.
That said, does she have any negative factors impacting her score like delinquencies or late payments or excessive credit on revolving accounts? If she does, her score may impact the interest rate you're able to secure. If her score is simply low because of lack of accounts with long histories, your score might be enough to get a competitive rate.
And finally, do not forget that the FICO score is not all that determines a loan. There is the debt-to-income ratio and other such factors. If you and your wife are solvent enough, I do not see any reason why you shouldn't be able to get a competitive rate.
It is a good thing you know your score. Tell lenders what these scores are as you bargain with them without giving them authorization to check your score. Remember, as you seek lenders, do not have them check your credit each time you speak to a new lender. Many inquiries on your account creates the perception that you are actively seeking credit and so your score will drop. However, if you go to the same class of lenders during a 14-day period, your score only drops once and not for each inquiring in that period.
