The Avro Lancaster could do 287 mph, the Lancastrian was a transport version with the turrets removed and aerodynamic fairings used in their place and did around 315 mph with 10% better fuel economy, the Avro York was a transport with the Lancaster wings and engines with a new fuselage with twice the cubic capacity, top speed 298 mph. The two stage Merlin Lancaster VI is reported as capable of 345 mph with the front and mid upper turrets deleted.
Lancaster Military load weights, Fixed / Removable
261 / 179 / Front turret (FN.5A) Guns and ammunition (2,000 rounds)
320 / 179 / Mid Upper turret (FN.7) Guns and ammunition (2,000 rounds)
370 / 490 / Rear turret (FN.20) Guns and ammunition (6,000 rounds)
240 / 0 / Turret hydraulic systems
105 / 0 / Ammunition boxes, tracks and mountings for rear turret