Anybody who can build any engine, should be able to get bearing gaps and ring gaps right. They should be able to torque bolts correctly. Where an FE gets real different than other engines, would be points of concern, if this builder did not have much FE experience. Valve train is one of those places.
Another spot is the cam bearings. The SO
oil system is different than the center oilers. If CO cam bearings are put in a SO, it will close off
oil flow. I'm not recalling the specifics right this very moment. In fact, the whole
oil system on FE engines is different than most other designs. Since this was just to freshen up the engine, the cam bearings may not have been touched. If they were changed, I would want to make sure enough oil was going to the top end. If not that would make things noisy too.
Sloppy work in general is always a concern. However the valve lash may not be an indication of sloppy work. In my puppy days, I never bothered to closely gap solid lifters on the engine stand. I just snugged one valve up, seen how much of a turn was needed to get the cold gap about right, and then just repeated the snug and loosen on the rest. That was close enough to fire up the engine and warm it up. Heat cycle it a couple times and then adjust them hot.
It doesn't sound like this was the builders plan, but maybe he was thinking someone needed to adjust the valves hot anyway. Then when he saw it, his next thought was the side to side play needed fixed first. Some people do not elaborate on what all they are thinking, just what they want to do. I don't know, I'm just trying to give the builder the benefit of the doubt, as well.