If it's a 403, that's an Oldsmobile BIG BLOCK, and they only came one way. HOT. That's the same engine that made the 1979 Trans Am a very fast production car. GREAT score.
What ya gonna do with it?............Drive it till the freakin wheels fall off of it. Great score to say the least. Dont need to do nothin else with it. Keep tires and brakes and oil in her and stick the car payment in your pocket each month.
Small Block