1974 Duster

I had a noise from my fuel pump area, too. I'm running a magnum roller in my early block with hughes lifters and fuel pump eccentric adapter, so pretty similar to your setup. I replaced the fan clutch and alternater, before I figured out it was from the pump. Pulled mine and replaced it, which made no difference. In the end, what I found was that the pump arm was rubbing on the timing chain.

My theory is, with a flat tappet cam, the cam is being pushed back into the block, so no issues with clearance between the fuel pump arm and the timing chain. Replace the cam with a roller, and now the cam floats in and out of the block. If the clearances are too tight, the chain hits the arm and makes a racket. I had to smack the arm on my pump to clearance it, no noise since then.

No idea why it would show up later, though. Maybe it's a completely different problem.