I purchased an engine with CHI 2v heads, bad move, terrible mess. Different heads but check everything, sounds like your engine builder is checking clearances. With these heads the rockers were miss-aligned in line with the valves, they would need the Manley guide plates either replaced or cut apart and rewelded. Some pushrods also had wear marks on them because they were rubbing in places on the pushrod slots in the heads. The pushrods also were too short with the wear pad on the valve too close to the rocker, the bronze valve guides were badly worn because of this. Check everything.
