Advice on Build for AE and Premiere Pro

Hi there,

I've looked over some of the designs as Puget Systems to get some ideas on a build, but have a few questions.  I was surprised to see them suggesting the GTX 1070 over the 1080, which makes me question some of my other specs I was planning.  I have the hard drives (2 SSDs and an m.2 drive), the case (Phanteks full tower), PSU, and motherboard (Asus Prime X299 Deluxe), so I would like to build a system with those components rather than a pre-built system.

We shoot 4K and edit HD as well as 4K (h.264 from GH5), but often use low-res proxies.  I have no plans for RED footage.  I use Neat Video noise removal often and color either in Davinci or with Lumetri in Premiere Pro.  We use After Effects as much as Premiere Pro.  We'll be using a simple monitor via hdmi.

1. CPU. I was looking at the i9 7940X, but I saw in a post here that neither Premiere Pro nor AE will utilize it for the money, and suggested the 9900K, which is much cheaper.  I like the idea of it being cheaper but want to be sure I'm not cutting corners if there's a better option for a bit more.
2. GPU.  I have a GTX 1080 ti 11GB in one of my systems now and just assumed I would get the same thing for this system.  However, Puget suggested that there is little advantage for the higher cost and suggests the 1070 8GB instead.  I have had a few crashes in the past with my 1080 ti 11GB which caused some concern- I don't recall the exact message but it was a GPU issue complaining that I had run out of GPU Ram (I know that's vague and without the exact code it doesn't tell you much).  I don't recall the exact project, but I want to say it was when I was exporting a project that had some heavy noise removal going on.  In any case, there's a big difference in cost, but if a 1080 11GB GPU is going to be better in specific situations, it could be worth it.  I know Premiere Pro doesn't use GPU except with GPU accelerated effects, which I think Lumetri is one of them.
3. RAM.  What advantage would there be to opt for 128GB of RAM over 64GB?  I know AE loves RAM and I often have AE, PrPro, Photoshop, some explorer windows open and Chrome all open at once, jumping back and forth.  If I'm saving on the CPU or GPU, I don't mind spending extra here.  128GB 2666 either Corsair or G.Skill is what I was looking at.

Any advice on this would be helpful.  Thank you in advance.

Stephen