The B-29 had an extensive pressurisation system built into it, including a tunnel that went from the front cabin, nearly half the length to the remote gunners, then the rear gunner in a separate cocoon. - All the Lancaster needed was the front cabin area pressurised. Also, it was built with the main wing spar out to the first engine nacelle each side as the primary element that everything else was built onto...it was sort of a T section, which gave great strength to the overall design, and the outer wings would've been strengthened as the latter Shackleton was...The A-bomb was designed to go off above ground; they were delicate, where a quantity of uranium/plutonium had to slide the length and collide with material at the other end to create the fission to critical mass, thus exploding...I think it may have been an altitude-fuse device that set that in motion, at least in those early ones...Gai-jin does indeed refer to 'whites', it actually means 'barbarian', which us 'honkeys' were referred to by the Japanese, who felt we were 'unclean and uncivilised'...James Clavell wrote a series of books centred around Japan, most remember his book 'Shogun', but his last one was called 'Gai-jin', about Admiral Peary's landings in Japan in the late 1800's...Anyway, IMHO, the Lancaster could've been modified to do the deed, the Griffons were capable of 2000+ hp each, the B-29's 2200hp engines had more plane to pull, the Wright R3350's had alot of development problems...they only really started getting them right prior to the nuking...