first damascus gun. needing guidance

[matt koepnick]

have been pondering buying a parker with damascus,or hammer gun. was blessed to come across a grade 2 with both. says 1882 manufacture.the frame size is 1 . barrells have a plain 4 stamp as weight. they now weigh 3lbs 8 oz. set is 30 inch long. both barrells choked at .030 . chamber length measures 2 5/8 . chambers bored to .805. barrells are curiously bored to .760/.765. by appearance it has 3/16 long forcing cone. some minor pits.
i have done extensive barrel measurements to check and recheck wall thichness
here a basic set of numbers:
breech =.160 both
2 3/4 down = .115/110
6 down=.080/,075
8 down=.065/.060
12 down=.050/.045
15 down=.040/.038
20 down =.036 both
down to where chokes start=.030
i have some loads for my vh that are 7/8 oz at 7200 psi, in 2 5/8 shells.
do i need to load lower? i can load same payload to 6000 psi with some stuff i have left. the larger bore size makes me wonder about lower pressures with same 7200 load.
any thoughts would be helpful. thanks matt k