SBF cylinder heads up to about mid year 68' had fully adjustable rockers and shorter (6.8") push rods
the non adjustable 76' heads have "bolt down" non adjustable rockers and do use the longer rods with shims if necessary (6.9"approx)
tell him his valves are longer also than the adjustable rocker heads
I call it: "the L-4 change bear trap"
cause of what he did for the break in......he really should do a lift measure at the rockers on all 8 cylinders because: "some were loose and some were tight"
no calipers on hand, a crude way is to make a lift "reference stick" to compare all 16 valves at TDC...cut it/shape it so you can measure each at the same location on the head....wooden paint stick works...easy to cut and trim