This sounds serious. Can you be a bit more explicit, please.
Let's focus on the box that's having problems ...
1) You install OpenACS using the bootstrap-installer
2) You visit /acs-admin/install and installs from local file system .. which packages?
3) The SQL files do not get sourced.
Is that the scenario?
I'm fairly confident it doesn't have anything to do with the PG port. We routinely have PG running on different ports.
But I did experience a problem with the new installer not sourcing DB files right, because the paths wasn't constructed just right. But I fixed what I found.
Are you 100% up-to-date on the code?