Is 3.08 to low to use 4th gear around Town?

[Arl37]

I have a 69 C10 with a new crate 350 and a 700r4. It has a 3.08 rear end and 255/60R 15s. When i am in 4th around town and trans is not locked up it seems to work pretty well shifting in and out of 4th. When I engage the lock up for 4th it shifts into 4th earlier and stays in it longer plus it drops the RPM about 200. dosent really lug in the classic sense but just dosent feel right to be driving around at 40 MPH at 1600 RPM. On the highway at 70 it turns 1800 locked up.
Posted via Mobile Device
Posted via Mobile Device
Posted via Mobile Device