Having laboured for years with ''Traditionalistas' with Astons (for example), I'd say that you should do whatever brings you pleasure!
If yours would benefit from power steering - go for it.
I've never driven a Morgan with it (not many if us have) so it's hard to comment.
My own philosophy is 'less is more', however, if the lack of an enhancement was eroding my pleasure - I'd add it. Immediately.
