Great looking car!
I believe you are correct, that it is a 25.
1925 cars were serial number 23615 - 32029 if my information is correct. I'll have to double check in my book that is packed away from my recent move.
I would purchase this book, then take it to the licensing agency and show them the list of serial numbers in the back. That's what I did with my improperly titled 29 Lincoln.
Good luck!