8.3 Beta Incompatible Data Disaster

Ignoring the warnings not to use a beta product on a production database I
had been running 8.3beta1. When I saw that it had hit 8.3RC1 I decided to
upgrade and folowing the usual data compatibility within major versions I
did not do a pg_dump, in fact my last dump was when I loaded the beta on
10th October. I get the following error
FATAL: database files are incompatible with server
Unfortunately, I cannot find my copy of the beta1 source files and they are
no longer available on the internet. All I had was a download of beta4,
which I never used. I fired it up hoping that the data incompatibility was
between beta and RC, but the error reads:
FATAL: database files are incompatible with server
DETAIL: The database cluster was initialized with CATALOG_VERSION_NO
200709301, but the server was compiled with CATALOG_VERSION_NO 200711281.

What can I do, a dump is impossible because I cannot re-install the version
that the database was last used with (it should have been first initialised
on 8.2, as I went to the beta to experiment with enum having recently
returned from MySQL).

Any help appreciated, including links to a download of beta1 that still
works.

--

Mark Walker