4000 rpm's at 60, no 3rd?

You may have gone too far the wrong way. As far as I can remember the longer the rod the higher it shifts, the shorter you go the lower in RPM and speed it shifts. There is a throttle speed rod or whatever it's called that the the carb/tranny linkage hooks to down below and that is what tell it what speed to shift. If you go way to far you won't get WOT and it will shift at super high RPM. If you take it completely loose the tranny gets no pressure signal and will almost immediately shift into 3rd and very quickly eat itself as it's a full mechanical system and will get no line pressure signal at all.
Many Chevy guys destroy Mopar transmissions by throwing away the shift rod linkage thinking it has vacuum modulators for line pressure and shift points like a GM.
anyways if you climb under the car and look where that linkage is hooked up you'll see how it works, all the way against the case is WOT and high shift points, all the way loose and forward is no pressure and super low shift points.
Once you figure that out you can adjust till you get it right, some books even have a way to line up holes in the linkage system to get it right on a factory setup with no mods or shift kits.
Once I knew which way the rod was supposed to be adjusted to go up or down I tweaked it till it shifted where I wanted it too within reason on my Dart.
I did have a Stage 2 kit in it for a while with 2.76 gears and WOT upshift was 5500 rpm 50 MPH to second gear Normal was about 25 to second and 35 to third.
With a stock or stage one kit it's about 10 to second and 25 to 20 to third when not pushing it and maybe 4500 WOT to second and normal 2.76 to 3.23 gears. If you have higher gears everything also shifts higher as well but the road speed might end up lower. I was doing 3600 RPM to do 60 give or take with 3.91 gears in it. The shift points were harder to get down as well with higher gears.
Good luck with it, if I'm wrong about anything I'm sure someone will jump in and correct things, it's been a long time since I had to touch the Dart.