Unfortunately the Beggars' Canyon missions were not archived but this Internet Archive page might jog someone's memory.
Cuda's Flight Simulations (IL-2 page):
https://web.archive.org/web/20041011160006/home.comcast.net/~rvvcuda/IL2FB.htmCuda's Canyon Race map is located in the download at M4T.
SimAirRacing Racing Maps:
http://www.mission4today.com/index.php?name=Downloads&file=details&id=4931(This download includes all of the maps that were available at SimAirRacing when it shut down.)
Cuda's Racing Training Video Series:
Training Video:
http://www.mission4today.com/index.php?name=Downloads&file=details&id=4919More racing maps at M4T.
Racing Maps:
http://www.mission4today.com/index.php?name=Downloads&c=582These are the file names of the missions you are trying to find.
These are the "Beggars Canyon" file names.
Daytime:- Daytime_in_Beggars_Canyon_P47D.zip
- Daytime_in_Beggars_Canyon_P51D.zip
Thunder:- Thunder_in_Beggars_Canyon_P47D.zip
- Thunder_in_Beggars_Canyon_P51D.zip
Night:- Night_in_Beggars_Canyon_P47D.zip
- Night_in_Beggars_Canyon_P51D.zip
The two listed below are available at M4T and linked above.
- IL2RacingVideo.zip
- Cudas_Canyon_Race.zip
Wheels