3.1 swap to 3.4

Has anybody here done a swap from a 3.1 v6 to a 3.4?? and if so is it difficult to do for a 94-95 ga? Also, is it worth changing one for the other? my 3.1 is running ok but I would like to get the bigger engine if possible.

Also....completley off topic, has anyone put a sunroof into a ga that was not equipped with one, a local salvage yard has one from a 96 ga in perfect condition, was wondering what it might cost to have it installed.