[Edahall]

Bad news: The 4500 is not going to fit in your car. The 4500 was made to fit transversely and for your car, the engine sits longitudinally. However, you do have some other choices including:
403 Olds
350 Olds
6.2 Diesel
6.5 Diesel
5.7 Diesel (Not good choice)
3.8 Buick V6

The 403 could be made to work with all the electronics. However, it'll be hard on gas but have good power. The 6.2 diesel would get you 35+ mpg and would have even more power than the 403 with a turbocharger or some head work but would have that diesel clatter.