Your carburetor maybe leaning out, probably an internal issue. Holly's are real easy to work on, if your at all mechanical. First however, I'd check for any vacuum leaks, hoses cracked or loose on the fittings, loose nuts that hold the carb on. Power break booster leaking maybe ? I can't believe it's your fuel pump/filters as you say you have no acceleration problems. Have you checked the timing ? All the basics first need to be looked at. You said the car sat for twenty years, maybe the carb gaskets have dried up and shrunk, causing poor fuel delivery. I'd try enriching the idle mixture screws, to the point that the engine misses. Then drive it and see if there is any difference. That ticking noise you have, carefully put a long rod of some sort on the fuel pump with the engine idling, and see if you can hear if it's the fuel pump or not. If not, you may have a stuck or worn out lifter or even a worn can lobe. You can listen at the valve cover too with that rod, to maybe located which lifter is noisy. From there take that cover off, and inspect the rocker, stud, and push rod. You could try adjusting the rocker first, before any major tear down.