Captain,
You may have a dead glow plug. That is how I know my plugs are starting to go out. She starts great, and then when one plug goes, she will still start right away, but has an obvious miss for a few seconds and cheeches a bit of white smoke until that cylinder warms up enough for proper detonation to occur. Every time it does this, I find at least one dead glow plug.
That said, On Sunday, I hooked the big trailer (24' Enclosed Car hauler - 10K lbs) to the old girl for the first time since I rebuilt the motor this spring. It did wonderful. 60 mile round trip from Springfield to Bolivar and back, up and down MO #13, which those of you who have been through the region know that is not a flat route by any means. I never needed to shift out of Overdrive on any of the hills. The truck maintained 70 mph on the flat sections with throttle to spare, and only dropped to 62 on the steepest hill. Peaked at 11 psi of boost, and 950 deg F EGT's. Ambient air was 45 degs, so coolant temps were never a concern. Seems to be a bit of room to turn the pump up if I so desire.