Oracle 10.2g Character Set Migration
Yes, WE8ISO8859P1 is a subset of AL32UTF8, though a small bit of conversion might be needed (which CSALTER will deal with &amp; CSSCAN will inform you of when you do a preliminary scan).

A must-read for Oracle 10.2 is here.

Doing a full export/import will be more time-consuming than using csscan/csalter.

Another good, albeit old, read is the Oracle Character Migration Best Practices white paper.