broken pushrod question... newbie

Woke my engine up after a long slumber. While trying to time it I found the number three cylinder dead. Pulled the rocker box covers and found a broken pushrod on number three intake. Then I noticed all the other pushrods we're not centered In their bore. The last knucklehead installed all the rocker arms in the wrong places.

Can I change all the pushrods without taking off the heads. Is it possible to bleed the lifters down while they are installed? Any words of wisdom would be appreciated