I just did a highway run today, actually, so I am trying to think about what my tach was doing.

Your numbers still seem a bit high, but from what I remember, at 65 I am running 2200-ish no throttle, 2400-2500 at a steady throttle, and if I give it more to accelerate it'll go up between 2700 and 2900. Not too far off.
The only thing that seems off is it being at 3000 if you are going 45. That even seems like 3rd gear territory, to be honest. I can't say exactly where I am turning at 45 in 4th under acceleration, but off the throttle it is around 1300 or so, so 3000 seems off.

Is the acceleration ok otherwise? Or do you feel like you are losing some and revving too high?

Also, FWIW, I watched a few videos on youtube of 87 300Ds doing 0-60, and from a stop they jump up to 2000ish rpm, so yours sounds about right in that aspect. Looks like there's something up with 4th gear

__________________
Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k