I think it depends on the variety of pine and how many needles it sheds (that's what makes for the acidity). Redwoods are notorious for making the nearby soil acidic but then again plenty of people do guerilla grows in redwood forests in California.
One piece of advice I've heard but have never tested is that if there's enough space between trees for sun to get through, you're probably okay because trees shed needles in the same area they block sunlight to.