My copy of Jane's Fighting Aircraft of WWII lists the following for the B-17:
PERFORMANCE.-Maximum speed 295 m.p.h (472 km.h) at 25,000 ft. (7,625 m.), climb to 25,000 ft. (7,625 m.) 41 min., Service ceiling 35,000 ft. (10,670 m.), Normal range (maximum bomb load and normal fuel) 1,100 miles (1,760 km.) at 220 m.p.h. (352 km.h.) at 25,000 ft. (7,625 m.).
B-26 is as follows:
PERFORMANCE.-Maximum speed 287 m.p.h. (459.2 km.h.) at 5,000 ft. (1,525 m.), Landing speed 104 m.p.h. (166.4 km.h.), Service ceiling 19,800 (6,040 m.).
Lancaster is as follows:
PERFORMANCE.-Maximum speed 275 m.p.h. (440 km.h.). Maximum range approximately 3,000 miles (4,800 km.).
And as that was less than useful, here is the info from Bombers of WWII:
Performance: maximum speed 442 km/h (275 mph) at 4570 m (15,000 ft); cruising speed 322 km/h (200 mph) at 4570 m (15,000 ft); service ceiling 5790 m (19,000 ft); range 4072 km (2,530 miles) with 3175-kg (7,000-lb) payload
Ju88 is as follows (from Jane's again):
PERFORMANCE.-Maximum speed 295 m.p.h (472 km.h) at 17,500 ft. (5,340 m.), climb to 17,500 ft. (5,340 m.) 23 mins., Service ceiling at mean weight 27,000 ft. (8,235 m.), Range with maximum fuel 1,900 miles (3,040 km.), Range with maximum bomb load (6,000 lbs.=3,000 kg.) 650 miles (1,040 km.).
Hope that helps.
Sisu