Ok, so I now know where my corroded donor board came from!
Free (or a swap for some 2716 or 2732 eproms if you feel generous )
1 x E-720-28-U6 Lost World U6
1 x E-728-48-U2 Lost World U2 (found the U2 with 4 broken pins, which I have repaired. The U2 chip is a pretty gold and ceramic chip - the others are the usual black plastic.)
1 x E-729-33-U1 Lost World U1
Don't know if they are OK, but have been treated with deoxit and preservit to stop the legs from corroding any further. Actually look OK for their age.
If you want them, PM me and I'll post them to ya. Please, only ask if you own or are fixing a lost world!
I have this posted on both forums, so if both sites get a bite, I'll have to give it away based on time of reply...
Cheers
Jacob