after replacing cam and lifters have misfire on all 4 rear cylinders.
What engine? How many miles on it?
Who did the cam and lifter work? Why aren’t you asking them this question?
Which is it?
In the title you say engine rebuild.
In the text you say cam and lifters.
If it’s cam and lifters only then that is NOT a rebuild.
I’m also curious as to why the cam and lifters were replaced. That usually means low oil pressure leading to collapsed lifters and then wiping the cam lobes out.
Did you make sure that the correct cam went into each bank???
Check the valve timing alignment marks again.