That article about the altitude record is a very interesting read.
Only 10k short of a U2.
What would it have taken to get the Canberra to FL80?
Lengthened wings - even moreso than the RB-57D?
Or would the airframe need to have been completely redesigned due to coffin corner restrictions?
EDIT - my question answered:
https://en.wikipedia.org/wiki/Martin...Specifications