Ticking like a time bomb - 1966 340

Just picked up this 1966 LeSabre 400, and the engine is ticking quite loudly. Engine seems to take throttle fine. 53000 orig miles, seems all original.
Should I be looking at oil pump upgrades, or swapping out lifters (without new cam?) ?

the 66 will oil the rockers through the rocker shaft via passages in the block + heads. make sure those are clear.

Thanks, Bob, I guess best to check the simple stuff first. I saw another thread a while back on TB that discussed this same approach; could have been your advice.
I'm used to the nailheads. My 61 starts great, catches a high del, a quick blip of the throttle and low idle, no ticking no drama. Guess these "new-fangled" engines are more fussy!!!