Hi
Did you assemble the same parts in the same position as before?
The cup washers between the valve and the lifter come in different thickness.
Are the valve keepers in all the way?
Let the lifter bleed out under pressure for a while, that sometimes works.
If not, put the lifters in a vice and push "slowly" the oil out of them.
Or just run the engine as is. If everything is assembled correctly, the problem may fix itself.