I try to avoid this sort of thing, but especially back when I was collecting vintage fabrics I often got asked for help.
Of course I'd check my stash first to see what I had. Typically I would use a modern fabric that I distress first. Many ways to do this. I'd probably start this project with a medium gold fabric and heavy bleach and hot wash followed by a complete hot dry to start, and figure on at least one more wash after that (required after the hot dry anyway).
I've done salt distressing (soak in salt water for a few days). I've bleached, dyed, coffee dyed, all sorts of things. It can be fun just working with fabric, dying and and other treatments. A lot of things can be done in small batches in your microwave! Some things are best done outside...
To cover the tear you can take a piece of illusion veil type stuff or organza from the fancy side of the fabric store. You cover the area and simply stabilize stitch down the illusion net with an appropriate color thread, I suppose you could even get fancy and do decorative stitches. I usually try to hide it within the block shape, or just do basic non-intrusive zig zag applique around the edges and across to stabilize.
Sometimes there is a naughty dog repair where there is just no disguising the issue. In those sorts of cases I usually recommend a big heart shaped applique patch, or sometimes maybe even entirely new borders.
Unlike the beauty you have there, some times the best you can do is have the well loved remains be the inside of a new quilt.