1968 340 push rod issue

Hey guys working on my buddy’s 340 dart he just got, pretty much stock 68 340 compression heads valve train,etc only thing done on the rebuild is they used a size bigger Mopar purple camshaft (as were told)

Issue is that I believe the push rods might be too long, why I think this is because, when he got the car there was a loud ticking and we found the valve lash was extremely loose, the adjusters were getting backed out. So not knowing the lash, and to get this thing running and out of my yard we tightened it to ZERO lash.

A couple weeks later he tells me the ticking is back, we bring it to my yard sure enough some of the rockers backed out once again.

I was suspecting the push rods are too long, causing this issue, also the car likes to idles around 900RPM and it’s a 4 speed.

I feel that his cam is not as radical as it sounds, just because the push rods are adding more lift to it being the wrong. We’re going to get my push rod checker and see what going on.