Rebuilt motor won't turn

Lower end of my 1971 340 rebuilt by shop, I had to assemble upper end. Assembled cam, , cam sprockets,crank sprocket, timing chain (dot to dot) and was able to turn engine over with the crank bolt attached to harmonic balancer. Once I attached the new hydraulic rocker arm assy, I was unable to turn motor over manually with the crank bolt, even with 135 ft lbs of torque.......If I loosened the rocker arm shaft retaining bolts, I was able ,again ,to turn engine over with the crank bolt.........

Anyone have a clue as to what might be happening ?