Downgrade repository's version (1.4->1.3) without losing local modifications

Hello,
I have a single checked out SVN repository, shared between 2 machines (lets
call them A and B). Until now I was using it only on A which has SVN 1.3
installed. Today I updated it on B which has version 1.4 installed. It
turned out that repository's internal structure's version was bumped from
1.3 to 1.4 and now I can't work with it on A.
Unfortunately I can't upgrade SVN's version on A (and can't even install my
local version of SVN) so I have to downgrade repository back to 1.3
somehow.
Is there a way to do it without losing numerous modifications I've done?
(and without committing too, I have read-only access...)

-- 
Regards,
Sergei Dyshel