I have some experience with this subject.
First, the fabrics look to be in good shape, but those seam allowances are very small. Even a little agitation in your machine could cause raveling to some of the blocks to the point that you will also be having to restore some of the blocks. Been there, done that.
Every top should be checked for fabric stability.
Older tops don't usually hold up to modern quilting. Been there, done that, too. I just dont listen, have to find out for myself.
So, I suggest you hand wash in a tub or large sink with a mild soap like Orvis, Oxy-clean or Shampoo for died hair(yes, I mean shampoo. Orvis is really a shampoo for horses!) I use Treseme on my silks.
You can then put in your drier on a low temp until it is damp/dry. Then take it out and lay it on you bed to completely air dry.
You can then carefully press the seam allowances and quilt.
Fabrics from this period should hold up well to quilting and use.
Once the quilt is done, you can wash in your front loader on a gentle cycle. At that point it is the spinning that can cause week fibers to break so gentle, gentle, gentle.
You should end up with a beautiful, and very useful vintage quilt. As for historical dating, once you quilt it with modern fabrics, it will no longer be considered a 1940's quilt but a 2008(or whenever you finish it) quilt.
So your label should tell the whole story and add your name and date as the quilter. I personally think that future historians will find that these multi generational quilts will be an important piece of quilt history.
Another extremely long post by me, Judy
Sorry girls, I get a little be windy...