Nice looking oldsmobile there. Personally, I would keep the rocket engine in it, but thats your choice. If your looking for performance parts, its usually a better idea to go through Mondello. As for bolting in the 425, you may want to map out your engine bay before you do any swapping. The BB Oldsmobiles were a few inches taller than the small blocks. As such, you may have clearance issues with the hood and even the shock towers. Also, your probably going to have to find a different transmission. Unless im mistaken, the Oldsmobiles from then used a different bellhousing pattern. Behind the 425, I would reccomend the T-400. You will find one behind any BB buick, olds or pontiac. BOP. Good luck, and enjoy that big block. Olds motors make killer torque