Good eye both of you. Yes, there were Oldsmobile engines in Buicks. They also found their ways to some caddies. Devilles with Towing packages also had 307s with the good heads. You may want to look into 5.0 Caddies. As for the 307 you have, heres a few suggestions. Bump the timing up a few degrees. Oldsmobiles always ran high timing, so there is a tendancy towards pinging, but theres still some advance to be found. Replace the O2 sensor if you plan to keep the Q-jet, or just replace the Q-jet and get it over with. I personally reccomend an Edelbrock 600. Hollys might look good on this engine, but they perform horribly. Too little engine for too much carb. A good coil is a must. The EGR should be replaced or unhooked if you dont have to worry about emissions. The PCV is usually clogged on these motors. Pull the hose from the base of the carb, and blow through it. After you pull it from the passanger side valve cover of course. Then spray a bit of WD-40 down into the Valve, or replace it. It only costs somewhere around$2, so its your call. Finally, check for vacuum leaks. With a car that age, the hoses for all the vacum controlls are usually dry. Pull them and replace them. The Olds will run much better with the AIR pump engaged. Otherwise it will run lean at higher RPMs. This is due largely to the Computer controlled mixture. If you go to replace the carb, this isnt much of a problem. But its always a must if you dont have that great of a budget.