Thanks for the answers so far.
I'm using a quadrajet.
It has the bellcrank shown in the pic.
I checked the relation of the TV plunger and carb linkage with the pan off. At WOT the plunger is fully buried. At idle the plunger is a bit depressed.
I was told and read somewhere that this bellcrank would work with the transmission. Although Bowtie Overdrives offers an adapter for these.
My guess was also that the pressure is too high, so the governors pressure cannot overcome TV pressure.
The shift rpms at min throttle are pretty normal. 1-2 at 10-15mph, 2-3 at 25-30mph, 3-4 at 35-45 mph.
It also downshifts nomally.
I found it interesting that I cannot shift it manually in first. at 5500rpm I put it from L1 to L2 but it doesn't shift. With a lower throttle setting it will shift just fine.