If you want completely delete revisions from the history between other revisions and don't want the revisions from shift upon dump loading like:
------- Committed new rev 1 (loaded from original rev 2) >>>
------- Committed new rev 2 (loaded from original rev 3) >>>
Then you can just replace all blobs in the dump for each revision
... <blob> ...
But to make it compatible, for example, with
https://sourceforge.net/p/PROJECT/REPO/commit_browser UI (otherwise it will stuck on loading):
This will leave all these revisions as empty and other revisions on the same places upon dump loading.
The TortoiseSVN GUI
show log will show them as