Move to new hardware question or prune database?

I have a need to move to new hardware (rather soon) to fix a disk issue
if there is not a way to “prune” the disk space the system is taking up

I have an old installation RT 3.0.10/Centos3/Mysql using an RPM
installation method and it is not really clear where everything is set
up in order to do an inplace upgrade.

Can the database be pruned back somewhere? There are a lot of “old
tickets” with attachments (hundreds with attachments of about 1MB or so)
or should I just build a new system and copy the DB to the new install
and hope the schema changes, etc. will all work?

Any suggestions are appreciated.