That is the original type rocker arm. Yes most of us old dudes prefer that to the button type.
Both type can become “bent” out of the 1.5:1 ratio. It is rare but happens with the intake faster than the exhaust ones. So how we did the check was simply take apart, clean, and use one to make a jig on a work table that had the center shaft hold it, and have a piece of steel tacked in position where the valve would be, and another where the pushrod sits.
Not super accurate but would show when one is out of shape. Usually only one would be, and quite often there was a mark where a valve kissed a piston- so my opinion became it was from that not just time that got it to bend.
Anytime I see valve to piston- everything that moves becomes suspicious & gets checked by measurement-even if just measuring compared to others in the engine.
Do you have an actual leak down tester?
Not hard to diy one & watch couple YouTube videos to see what to do if not. That is your next step imo.
I would fight to use the 6.2 heads over a 6.5 head. I would rather have 6.2 heads rebuilt than buying new 6.5 heads unless it is p400 heads. They simply flow better which is better power, better mpg when you keep your foot out of it, lower egt, better rocker arm system.
