Yes, probably the only benefit AEC gained from Leyland engine “know-how” was the introduction of nitrided crankshafts.
Harry Pick, a renowned AEC Service Engineer and later AEC / Leyland depot manager (Still alive at 90+) never used a torque wrench on a cylinder head. He always used a box spanner and tightened the nuts up by ‘feel’. He reckoned a box spanner and tommy bar gave equal strains and loading on the stud, wheras a torque wrench imposed unequal strains. If you think about it he is correct.