What angle should I set the VTA on my VPI turntable?

Your model is flawed.

I've done the work, taken the measurements.  Nuh-uh is not a rebuttal.  Show me.

OP,

I mentioned my specific cartridge for a reason.

I know the Delos set-up is super sensitive, don't know about Kleos

Let me be sure I understand what you are saying, Lutke. You say to place the cartridge on the LP surface at zero VTF, first of all. Correct? Typically when VTF = 0, the cartridge is floating in space above the LP surface, and the tonearm is parallel to the LP surface, else the tonearm is not truly balanced. OK, so in order to get the stylus to come into contact with the LP, I am going to have to crank down the VTA adjuster/pivot point quite a bit from where it would be for normal use, i.e., to play a record. So now I have got that done.  VTF = 0, with the LP in contact with the stylus tip. Now you say to crank down the pivot point still further. Yes, that will increase VTF from zero, because the LP must exert a force on the stylus tip to push it and the tonearm upwards; now the tonearm sits at an angle, with the cartridge up and the counter-weight down. The "VTF" you are measuring is that force needed to perturb the tonearm from its natural position of parallel to the LP surface, when VTF =0. Anyway, any time you want to move a sofa, I am your man. You can be on the bottom as we go up some stairways.

lewm

... you and a friend are carrying a sofa. On level ground, the burden is equally shared. Now you have to carry the sofa up a staircase. Who is working harder? The guy at the top end or the guy at the bottom end? Raising the pivot point shifts the center of gravity toward the stylus. VTF goes up.

Correct. This is basic physics. It’s odd that anyone here would need the explanation, but @wlutke clearly needs some help.
wlutke

I’ve done the work, taken the measurements. Nuh-uh is not a rebuttal. Show me

We’ve explained the geometry and the physics to you. Now it’s up to you to understand.