If they snugged some of the rockers at the top of a lobe. then went threw the order and gave a 3/4 turn. wouldn't that leave the rocker lose? It sounded like lose rockers or tappet problems.
As long as they turned the engine over to TDC on each cylinder, took up the slack, then pre-loaded the lifters, it will work. If they did NOT turn the engine over, and just did the pre-load, you would have at least eight rockers out of adjustment.

The best way is to have them all loose, bring #1 to TDC, set intake and exhaust, then go to #8, #4, etc., through the firing order.

There is a way to set all the rockers with only one engine rotation. You can set 8 with #1 at TDC and the other 8 with #6 at TDC, but you have to know the proper sequence.

10 PSIG is too much for the carb. Put in a regulator and start at 6 psig.

I'm with Denny here. Unless something is being lost in translation, I'm hearing things that a "pro" should not be telling a customer.