Upon further research, it looks like I can use the date filter:
Converting string to date
So, I would like additional support if possible. My date would currently be formatted as MMM dd HH:mm:ss, will this field now be converted without replacing the @timestamp field if I do the following?
date { match => ["field_name", "MMM dd HH:mm:ss"] }
Of course assuming the grok{} filter correctly parses the messages into their respective fields, would this work?