As far as threaded + quill vs threadless, one of the issues you'll run into is handlebar choice.

If you choose some sort of winged flat top handlebar, then you'll need an open face stem, and most of them will be 31.8mm bars. As mentioned above, if you have 1" threaded, you can use adapters, or there are a few quill options that might work.

But, for simplicity of the build, 1 1/8 threadless has much wider support.

However, there lots of cheap bikes and frames with 1" threaded, so I wouldn't shun those either.

As far as using an older CF fork. I don't know. I have a 20 yr old CF fork on one bike. 1" threadless is a bit of a pain, but otherwise, the fork seems solid enough.