86 vs 87 rear flip kit

[pockets]

so I've been looking at lowering components and I came across a user here who got a DJM rear flip kit from summit for his 86. The price on that is about $85. Says it is a 5" drop.

For my 87 it says I need a different kit that is $200 for a 3" drop. That one has c-sections and some weld plates that the other doesn't.

Is the 86 and 87 so different that a 3" drop needs the frame notched on mine?

While I'm at it, is there any advantage to going with lowered control arms over spindles? I would imagine there is a bit of weight savings, but anything else?