I could not find matches for any of the Ultima V disk's missing blocks in Ultima V disk images I have found online.
This disk image is unlike any of the others I have found. Indeed it's actually almost empty (the disk image compresses to only 3kB!), despite having only 11 unreadable blocks.
I have replaced 3 blocks by looking for matches elsewhere in the image, 5 have been left zeroed out to match the adjacent blocks and the remaining 3 still have 'checksum errors', but that's just a euphemism for 'invalid content' on this disk!
I've uploaded the disk image to the Zone for you to test. I can't get it to boot, and if it doesn't work for you, then I'm sorry, that's the best I can do with it.
You've ended up with 10 good images from 11 disks - 91% success!