If you’re building a rifle for YOU, get the action that makes the most sense to you. For a custom, it doesn’t make a nickel’s sort of difference whether you start with a new or pre-64. MY preference is for the pre but that’s what I sort of grew up around. I also prefer the 70 safety and trigger. For the latter, if you set them right there isn’t a better hunting trigger. Both of these actions may require some tinkering to get right but it will be minimal.
Good luck on your build.
Good luck on your build.