If I recall correctly, you have said that the pushrod is not moving up and down, and that the pushrod is in good condition. If this is the case the possibilities are limited as to what the problem is. Either (1) the pushrod is not sitting on the tappet or (2) the tappet is not moving up and down.

I would remove the rocker arms and replace the pushrod with a long dowel, making sure it goes straight down the hole. Turn the engine over by hand and see if the dowel moves. That will tell you which of 1 or 2 above are the case.

If the rod moves up and down, either (a) you did not properly get the pushrod into place or (b) the top of the tappet is worn or broken off so the end of the pushrod doesn't stay in place. You can try repositioning the pushrod, but I suspect you have already done this.

If the tappet itself is not moving, either (a) it is stuck in the sleeve or (b) the cam is not creating lift. You could try placing a long rod on the tappet and tapping lightly with a hammer to see if it is stuck in the "up" position, but that really seems unlikely given the pressure of the valve spring on the rod. Other options are a badly worn cam or a tappet that is completely broken in two.

Of all the options listed above, almost every one of them requires the head to be pulled to fix it. I suspect that is your next step. Please keep us posted on what you find.