Salvage older PostgreSQL data disk - help?

Greetings,

In short:

Using a new FreeBSD (4.9) PostgreSQL (7.3) server, can I
rescue PostgreSQL data from a hard drive pulled from an
older (motherboard just died) FreeBSD (4.??) PostgreSQL (7.??)
server? If so, how?

The long version:

Helping a friend who had a FreeBSD PostgreSQL server crash recently.
This was a motherboard failure, and the data on the drives looks
usable, but we are rebuilding the server, using a newer PostgreSQL
(7.3) - his most recent PostgreSQL dump was a few weeks ago,
(hey, at least he was backing it up - sort of). The version of
PostgreSQL used to build his data is unknown - whatever was current
around August of 2002 (7.1 maybe?). (Once the server is built and
the old drive mounted, I may be able to figure out the exact version
from the FreeBSD package DB, which should also be on that drive.)

Normally, I would tell him to just run with the dump from a couple
of weeks ago and live with it, but there has been a lot of non-
duplicable work done since then by an individual who left his
organization 2 days ago (and apparently cursed his server when
she left ;-) )

It would be real nice if we could use one of the old server drives
to restore his PostgreSQL DB - without having to build an old
PostgreSQL server just to extract the data, then rebuild on a 7.3
server.

Is this feasible? Pits or tipfalls, anyone?

Cheers and many thanks,

Conrad