If, next month, she has had a Green Card for 5 years, then file under the General provision. Don't make this more difficult than it has to be. Filing as a spouse of a US citizen will require you to submit the same type of evidence as you did for the I-751. If you file under the 3 year rule, this will apply:
A STEP-BY-STEP GUIDE to COMPLETING THE NEW N-400 (ilrc.org)
Item B: An application based upon marriage to a U.S. citizen for three years. INA § 319(a) allows such applicants to become eligible to naturalize after just three years of lawful permanent resident status. Filing under this provision requires proof that the marriage and the U.S. citizen spouse’s citizenship are valid. An applicant must provide the naturalization certificate or U.S. birth certificate of the U.S. citizen spouse and a marriage certificate. If either spouse was previously married, the applicant must produce documents showing proper termination of the earlier marriage(s)