Big Block ticking? Flat tappet cam. Normal?

I could never understand why some companies have bigger hot lash on the exh. The engine is at operating temp, so all the clearances are taken care of.

I suggest tightening lash to 0.008", hot, as a test. If the noise is still there or doesn't change much, it suggests something other than the valve train is causing the noise.

What rockers are you using?