You wouldn't have needed a B29 to get it up to altitude. M52 maxed out at 7720lbs, well inside a routine Lancaster's Tallboy weight of 10,000lbs. It could have been mounted in the belly as in the Betty/Baku combination or on top as the Heinkel111/FW190. Even with it on top a Lanc could have blundered its way up to 25,000ft. There would have probably been enough IAS to airstart the engine though getting it back on the ground at 170+knots would involve Manston, Elvington or Woodvale as they had the long wartime emergency runways.
The prone Meteor still exists at the RAF Museum at Cosford.
