A friend asked me about peach trees at Lowes and chill hours. Here's my answer.
chill hours are a complex calculation--essentially, amount of time that it's "cold" in an area, under 45°, although duration of the cold, and its severity, are very important. (so, one long stretch equals more chill hours than several short stretches of sub-40° temps and a few hours at 22° means a lot more than a few hours at 32°.) anyway, the measure matters when it comes to deciduous flowering/fruiting trees--chill hours are directly related to flowers and fruiting during the next growing season. over the past decade we've averaged something like 300 hours in our part of volusia county, though the standard deviation has been pretty high. some winters we get 150 some we get 650. (here's what i've written about it.)
even if we don't receive enough chill hours, that doesn't mean a tree won't produce the next season, but production will be suppressed. it's a threshold number--more than X chill hours in a season is optimal.
350 hours is really the outside number i'd look for here in our area. most of my trees have fewer than 200; my flordaprince, for instance, requires only 150. but i think there's probably a tradeoff--these trees have been chosen for their ability to produce fruit in an area that is not entirely appropriate for stone-fruit production, and my guess is that a tree with 350 chill hours, all things held equal, produces tastier fruit.
since you have a LOT of space (you could put 30 trees in your front yard, easily!), i recommend buying the flordaking they have at lowes. they looked like really healthy trees. my only reservation: i don't know what rootstock they used, and i don't think it's indicated anywhere. rootstock is incredibly important when it comes to nematodes, which may or may not be an issue where you live. that's why, ultimately, i choose to buy my trees from JUST FRUITS & EXOTICS, where i know for sure they've chosen the right rootstock and done a good job with the union. but the trees are more than twice as expensive for smaller trees.