Re: No oil to rocker arms
I would revert back to sqaure one.You have the rocker covers off now..pull the distributor.Install a priming tool and run it with a 1/2" drill.Have a friend manually rotate the engine at the crank pulley in 90 degree increments while you prime and observe.
Your lifter to bore clearance may be wide and it is not uncommon for a big block chev to take its time burping air out the galleys.
This will cost you nothing but time..and no engine damage will occur vs running it with no top end oiling.
If you can honestly say that after at 10 minutes of priming and rotating the crank by hand that you still have no oiling to 16 rocker arms..further checks will be reqd.
8-71 blown 461 Rat on E-85