make sure throttle is fully open
spin engine over for same amount of time each turn
once done it dry...put a few squirts of oil down and do it again and see if there is any difference... (if its the rings the wet test should be higher psi)
it doesnt have a gasket.....it uses a sealant between the cam carrier top and head....
before jumping in & doing lots of potentially unnecessary work...clean off the effected areas and then monitor it to actually see where its coming from
200k mileage and your worrying about a few bhp!
some engines would be dead at that...
get the cam timing checked/dialled in new plugs and & quality oil in and enjoy it :chris2: