Thank you to both Kara and Conor for your responses! Both POV's very helpful!
Just FYI, MKTO Support clarified for me that the MKTO Lead Owner information fields (name, email, phone, tiitle, etc) apply to both SFDC Leads and SFDC Contacts within the MKTO lead database. With that realization, I understood Conor's suggestion.
In our situation, Account and Contact owners were mismatched only when assignments were outdated. We updated our SFDC instance to assign the SFDC Account Owner to all associated SFDC Contacts. With that data cleanup, we could then simply use MKTO lead owner information to personalize emails to both SFDC Leads and SFDC Contacts.