Air bag selection - Type and ratings?

[.030over]

I have been trying to soak up all of this air suspension info as I will be doing both ends on my ‘67 swb big block truck. I am new to air bags other than an air assist system on my ‘94 and I have found just about everything that I have wanted to know on here except bag selection. Now, I know this is probably a personal choice thing but I’m wondering more about type or rating and less about brand. 2500, 2600, 150psi, 400psi etc. I want to have a nice ride and don’t care so much about speed or extremes. My truck will have a slightly narrowed trailing arm 9" rear with bags mounted just ahead of the axle and a c notch only. Front is a 73 up setup with 3" spindles. Also, Is the need to do 8 valves because of air transfer on turns? Is that still a problem if I use 1/4" lines? I was planning on keeping this as simple as possible but I can see how that might be a problem. Sorry for all of the “newbie” questions. Get me straight!
Scott