manual ball valve air ride pressure questions

[sharkskinman]

1/2" hard copper line in the cab
(8)1/2" high pressure ball valves (1 in 1 out each bag)
1/2" Air brake lines to the bags and from the tank

SS bags are rated a 250psi
i cant find a comparison of height to psi
but im guessing middle of the road like 100+psi for the front (66 c10 250)

at first i was thinking 7s all around
and then bought a pair of 7s(front original) and a pair of 8s(rear original)

but now that i think about it because of the difference of heights of the bags and the weight of the front, my thought now is 8 in the front

any ways
bags are 250, most tanks i see are 200, ball valves way over 200...
so im needing
(4) 250-300 psi gauge
(1) check valve from compressor to tan?
(1) pressure switch for the tank to the compressor(165-200?)(going with york on-board)(pressure switch and gauge for tank prob going to be In the cab at beginning of hard lining)
(1) relief valve per tank(200? 225? 250?)
(4) relief(pop) valve for each bag line (200? 225? 250?)
(8) push connectors @ hard line to bags and @ bags
(2) " " " " @ hard line to tank and @ tank

whats Really the working pressure of the system?
why is bag 250psi if most tanks and systems are 150-200?

can someone think of what else i might need