You will need to be patient with this one..
TW bg's are out there but not many good examples of one...Most of the games I've seen had real shitty bg's. Crazing and cracking in the paintwork, similar to yours.
Williams of that era i believe used lesser quality paints to save cash and now it shows...
I had the same problem with my Blackout. Purchased it hoping to find a NOS glass...Yeah right, 4 years of searching and being patient the best i could find was a 7/10 glass to replace my 3/10...
So be patient and good luck as i am sure one will eventually pop up.