If I'm being honest, I don't like any of the fabric selections above. While it's difficult to tell the weave patterns and weight because there's no point of reference in all but one photo, the colors on the pants, jacket and smock are also not ideal.
Shirt (this one is the best of the 4): needs to be thin and I'd prefer a tighter and more irregular weave (again, hard to tell the scale in the photo)
Pants: I'd prefer more grey toward a dark grey-brown than what looks like almost black in the photo.
Jacket: multiple thread colors in the fabric preferred so it looks like scale tweed or similar. A rougher fabric.
Smock: less royal blue. Needs to be more pale in color (less saturated), but remain dark in tone.
All the fabrics should be natural fibers - it will help with the look and authenticity.
I think Serang did an amazing job with his fabric selection and his work may as well continue to be reference here. The movie Lust for Life (Kirk Douglas playing Van Gogh) also did a spectacular job of capturing the artist and the period from the photos I've been viewing - going to find the movie to watch next.
Using Sernag's clothing as a reference below, I would change the following:
Make the shirt longer - maybe by 1cm
The smock in the photo below appears shorter than it actually is - it should come to about mid-thigh on the TTM-18 base body (Serang got it a nice length as can be seen in full-figure photos)
View attachment 259107
