Rebuilt the top end but the engines still knocking

maybe a head gasket leak. if you don't have a leakdown tester you should get one. did you do proper heat cycles and break in proceedures? I would check the torque on the head bolts
 
head torqued to specs. checked for leaks at head none there. i do have a leak down... nothing out of ordinary at crankshaft, cylinder, head or piston/rings. no slap scars at piston skirt or cylinder either