Yes this is possible, in the 1948 brochure catalogue the BSA M20 is also sold with the fork of the old model ( with the spring), as that of your attached photo.
The finishes for 1948 are: Black, matt silver and chromium.
Alternative: Devon Red and chromium tank and whells.
If you want some detailed photos I have a perfectly BSA M20 under original conditions.
Davide