Allis C camshaft swap

Troubleshooting an engine knock on a '49 C, inherited from my Dad.  ( It also won't start when it's hot - have to wait for the engine to cool down to restart it )  I was at a antique tractor show in August so I could talk with owners of restored C's, listen to their engines run and get advice.  The knock in my CE 95394 engine is not normal, their A/C's engines did not knock.  Recommendations were bad crank bearing(s) and/or worn camshaft causing valve clatter.  Back in 2017, Dad said the engine had been rebuilt, without saying when.  Currently it leaks a significant amount of motor oil from the front crankshaft seal, slightly less from the rear seal at the flywheel.  The engine is off the tractor now, and yes, it looks like new cylinder liners and pistons.  Also the cylinder head has new valves and the new valve guides.  I haven't pulled the crankshaft off yet.  The camshaft appears to be the original, to my untrained eyes I think it looks worn.  I'm getting a less worn replacement.

a real KNOCK is crank / rods / piston pin area... Worn cam shaft with excess valve clearance will make a RACKET , but normally not a Knock... Cant tell about most problems without actually takeing MEASUREMENTS... but i would agree, the lobes of that cam do look like they are worn off on the edges... Tappets need to be looked at close or measured to determine if they need refaced..... I have done several of the B engines over the past 20 years and never had one that i thought the tappets were bad enough to reface.