This is a sbc fuel pump pushrod...
it sits at almost a 45 degree angle from the fuel pump up into the motor to the camshaft. its sits on the black "tab" of the fuel pump.
The Cam retainer plater would be located on the front of the engine, right behind the cam timing gear. to be honest. i dont remember if your motor has one, i think it should but i may be wrong. i know the later roller cam motors did. If it is there, once you pull the cam timing gear off, you'll see 3 bolts in a triangle pattern and a metal plate right around the cam opening. Also, with the cam gear still installed(after lifters, etc, are removed) try sliding it out, if it starts coming out, then theres no retainer, if it doesnt budge, then there probably is a retainer. I cant remember if my '85 383 had one, i think it just had a thrust button between the cam and the timing cover.