Where do I find specialty plumbing items for my well pump in storage tank irrigation?

O.K., If I install a sprinkler system using a well pump in a water storage tank I will need to do the following (no pressure tank and switch to be used):
1) Balance the pumps flow output to the individual zones (ie: 10gpm pump output to 8-10gpm out flow in the zones sprinklers)
2) Wire the pump to the controllers pump start switch.
3) Install a pressure relief valve in the system in case the zone valve does not open.
4) Place the Well pump into a sleeve in order to create water flow over the motor for cooling.
5) Properly design the system with correct piping sizes and valves, etc., etc.

My question is, where do I find a pressure relief valve and at what pressure should I have it open at if my system pressure will be 55psi? I found irrigation pressure relief valves at www.fresnovalves.com or watermanusa.com but they seem larger than what I will need for my yard with my 3/4 HP (220V) pump (approx. 10gpm pump but not really sure yet).

Also, where do I find a pump sleeve? Do they make these for this specific use or do you just Mickey Mouse a sleeve out of 6" or 8" pvc? Thanks for any help. Joe