Installion could be wrong on the rockers.
I have those exact rockers. 1.9 Harland Sharps. They are great rockers if you get the revised set.
There's a small dot on the pedastal, that needs to be facing the valve stem. Also, go back and check everything. Such as:
1: Locks are completely seated on the on valve tip.
2: Recheck the springs/retainers, maybe?
3: Double check the pushrods if any are bent and make sure they are seated perfectly on the back of the rockers and seated on the lifter.
4: Recheck the rocker bolt torque, using blue loctite as well.
5: Cracked plug. As I cracked one when doing this install as well.
Basically you just need to pop the valve covers off and make everything is perfect. One little thing could be causing the misfire.