Ok, I made an enormous Version, which you'll probably want to shrink down, and maybe apply some Photoshop sharpening to.
Unfortunately, your original image was not only low-res, but apparently came from a lowish-fidelty JPEG of a scan.
But I don't think it reduced the fidelity in increasing the pixel size. I think it actually looks a little better, but ideally, a higher-res scan would be the best way.
Anyway, there is a 50-meg zipped Version
here.
Let me know when you're done with it, and I'll probably take it down.
I could also make another size, if that would help.
PvK