Upgrade postgres cluster on FreeBSD using pg_upgrade

Hi

I need to upgrade a PG cluster from 9.1 to 9.4 running on dedicated FreeBSD
9.2 server. Earlier I followed the simple pg_dump / pg_restore, but now
that the cluster has grown to around 700 GB (1 TB total HD size), I am now
inclined towards using pg_upgrade.

pg_upgrade requires both binary to be present at the same time, which seems
difficult as I have installed using ports. I don't want to compile PG
myself unless that is the only way out. Reading the mailing lists and
previous questions, I see following options:

a) Use the work directory of port to compile the binaries and use it with
pg_upgrade

b) use jails as noted in some of the discussions online, however no idea
whether it would work in my case.

c) Somehow modify the ports options so each versions binary is installed
separately. I have no idea how to do it, maybe need to ask this on the
FreeBSD mailing list.

What is the route generally preferred by those running PG on FreeBSD? Is
there something simple which I have missed out?

With regards

Amitabh