Well, either way the same logic applies in that direction as well, you will have to pass immigration, and are looking at a reasonably long walk.
I was confused as DL127 today operated FLL-LGA, but it seems like in September it will indeed operate AMS-BOS, so being a DL metal flight you have to go through secondary security questioning in gates D01/E01, and only then you will be told your actual gate, with 1h10 you should be fine, just make sure to go straight to immigration and then to gate D01.