Filesystem level backup and 32 / 64 bit

I have situation where I have one box with linux  native 64 bit distribution
(Gentoo on AMD) running pg 8.x and other box running a 32 bit distro
running version of pg 8.x

Is it posssible  to take a "filesystem level backup" (copyiing all in
$PGDATA directory) from 64 bit system and use it as $PGDATA in the native 32
bit system with the same version of postgresql ?


Ie to have one big 64 bit server and eventually a small but cheap 32 bit box
as an emergency backup  ?