Can't help ya on where to buy the block, but removing one should be fairly easy - It just depends. Some people say that theirs come right out. I tried to take mine out, and it would not come out - at least not w/o using a mallet.
Check e-bay - and there is a site where U can order Beretta parts. I am sure someone will post it up for U.
Try Dave Olhasso at olhasso.com for Beretta parts for the 92/96 and Cougar. I have an extended mag release ordered for my Cougar as the 92/96 Elite II will work in it. Never understood why Beretta made such a short mag release button. The Elite II is much better and would not have cost 1/2 cent more to make in bulk. He has Elite II hammers as well and other items like locking blocks. Orders from him always arrive within 10 days so far. I am still waiting on 4 additional MDS mags from Beretta ordered around the first of May. In fairness they projected a July ship date. Other items will take quite awhile as well is you read their stated lead times. Enjoy your new Beretta.