the 707 was originally equipped with short Krüger flaps which got longer with heavier versions.
Yes, the original early models did indeed have that short LED section (between the inboard and outboard engines) and yes, full span LED's were fitted to later models,
however as the weights increased on these later models (especially the -320B/C varients) the body angle on approach (and the approach speeds) remained about the same.
I should know, I flew these early models and well as the later ones, quite extensively.
By the way, the first B707 to have full span LED's was the -320 (straightpipe)
model, and it was delivered to South African Airways, for their LHR-JNB route, expressly built for SAA.