Hey,
I used to Live in Dallas and rode a lot on the north side of Dallas. So All the way from KY to Denton, not sure, but...
What I did ride multiple times was From Paris to Farmersville on the NETT (North East Texas Trail) It's a rails to trail conversion thats mostly done. Once you hit Farmersville then taking 380 into Denton is very doable. There is a lot of traffic on 380, but it has good wide shoulders.
http://northeasttexastrail.org/Mark