That's a lot of trees compared to my 17.
From the start, I'd not recommend soaker hoses for your orchard. While wonderful for small flower gardens and such, they would quickly pack up with mud and debris and stop working properly. And most have an average lifespan of 10 years provided they're mulched to avoid sun damage.
You'd be better off with a drip irrigation system, one with solid lines in a grid system, which you could then off shoot with secondary lines to do around each tree with several properly-spaced emitters. I'd recommend you mulch the whole area under the trees to help contain moisture and again, protect the lines from sun degeneration. The main grid lines themselves can be buried an inch or so into the ground for protection, but the emitters themselves need to stay on top of the ground so they don't clog.
by leaving emitters above ground you can check on them from time to time and replace or clean out any that need attention or are plugged for whatever reason. Emitter ends are easily replaced but do buy a brand that's been around for a while so you can get replacement parts.
You can also add an automatic timer to the system, either at the end where you pump the water from or at the top of the hill - really doesn't matter. You can choose between an electric one you can set for several times a week or a manual one which is cheaper but must be reset before every use. It'll run up to 6 hours depending on the brand, then snap shut until reset. The automatic is programmed and will keep working until you unplug it (requires power).
In this link:http://www.leevalley.com/en/home/OnlineCatalog.aspx?id=4e7b8aed
Grid D might work for you, with secondary lines along the length going around each tree. Emitters can be pegged into place so they don't move but they mustn't be covered with soil as they quickly jam up. Loose mulch is a better choice.