with the indicated pressures I would be surprised to find an over charge.
Also rheem has a chart inside the cover so you can check the charge. the tech made a guess the filter drier might be restricted. If that is the case there should be a temp drop across it. I have seen them sweating and icy cold and never tripped the hp switch. In my experience rheem/ruud heat pumps are more sensitive to an overcharge in heating mode than a lot of other brands. I worked for a company that installed hundreds of new ruud heat pumps in new developments. When winter rolled around I had a lot of calls with the pump tripped on the hp switch. Overcharged when installed. (NO I did'nt install them )I found dozens of them overcharged and every one of them the pressure on my gauges reflected the excessive pressure.
Of course I am assuming that since he said the coils were clean the blower and condenser fan are running and the filter is clean and the other usual suspects have been checked. Since he already replaced the defrost board (and the contactor?) and the defrost board should have come with a new defrost sensor I would think all those bases have been covered. It is still tripping on high pressure.
I've been wrong before but my money is on the HPS