Topic: Upgrade or not?

I am running a punBB with about 140.000 posts and 500.000 registered users (some proabably bots). It is running PunBB 1.2.15.

My challenge is that I have made some small modifications to it. I do for instance use the user database in punBB as user registering on my site.

I have major spam problems and I really miss some better spam handling tools, like first post approval. Is there a way of getting such tools without upgrading to 1.4.

Is there any way of doing a clean 1.4 installastion running in prallell, and then copying users and posts (and maybe even templates) to the new forum. Making sure everything runs before swithing.