Rocker Assembly
I would clean all of the parts with some brake cleaner first. Especailly the rocker shafts. I noticed some chips of metal left after drilling one of the bolt holes.
Some good assembly lube between the rocker tip and the valve tip and between the push rod and the pushrod cup. I also lubed up the rocker shaft. When tightening down the rocker shaft, tighten from the center out.
Also, were the notches on the rocker arm shafts on the opposite side like the ones I got from Mancini?