Go with the 311. It's an excellent valve. The only problem I have with the 311 is the threads in the ports. Don't use too much teflon tape. Go with 2 wraps or the male adapter will bind and the connection will leak.
The 2711 is also an excellent valve. I'm suggesting the 311 over this valve because of the 90 lbs and the high flow rate.
I've seen this valve split wide open a few times due to water hammer. The 311 shuts off slowly which will help avoid hammering.
the 2711APR is based on the original Richdel design - Richdel valves are repairable forever. Only one thing - if you have 18 gpm, then use the 2713APR, and get the best flow performance of any antisyphon valve.