I would remove the oil pan and examine the pump and the pump shaft. Possible to strip the pump and shaft.
Knocking could be many things. Is it low in the motor? or high like in the intake.

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1966 Stang Coupe Org. 6 cyl. 351w,Sealed Power Hypers, ARP bolts,Total Seal rings,Eagle H-beams rods,Balanced,Hedman long tubes, Pro Comp 2.05/1.60 Heads, Shaft roller Rockers, Victor Jr intake, Holley 750 DP, Ed Nix Custom .600/.600 254/258 @.050 Solid Cam, Crane solid roller lifters,Richmond 4.11, Strange mini spool, Modified C4, 3500 stall, Redneck Transbrake, B&M Hammer shifter, Shelby lowered, Pro Comp 6Al system. Mickey Thompson 275/50 Et Street Drag radials.