Dear Mr. McClellan,
We searched the National Archives Catalog and located the series Motion Picture Films from the "Combat Subjects" Program Series, ca. 1939 - ca. 1945 in the Records of the Army Air Forces (Record Group 18) that includes the item B-29 Raid On Tokyo. This may be the training film you seek. For access to this item, please contact the National Archives at College Park - Motion Pictures (RDSM) via email at firstname.lastname@example.org.
We hope this is helpful! Best of luck on your research!