I think his questions stems from the fact that some may fit, and function, better than others. We always recommend using sam manufacturer upper and lower, but we know there are plenty out there that can and do work fine together. We have also seen cases where things didn't match up perfectly. I can't site specifics, which is why I am refraining from supplying and answer. I'll let someone who's actually done it chime in.
My guess for the OP is that yes, the list is long of options that will do just what you need, but hearing from someone who has swapped "x" brand upper onto their DPMS lower would make me more comfortable in my purchase. As to the question of the high rail, low rail...the lower should have no difference. All that would matter with the high/low upper is which hand guards you use and potentially which sights. You shouldn't see a difference in the lowers at all.