I'm guerssing you want to do some research on building these motors?
Click 'seacrh at the top of the page, and enter 4.1. Also go to www.turbobuicks.com where this has been covered a lot.
For less then $200 you can get a set of hypers AND the rings from Summit. They are however a very heavy piston compared to the stock 4.1 piston so a rebalance will be required.