I don't know about the late-318 swap idea (the Fifth-Avenue scenario described above). An early LA 318 like mine is 230hp, those 1980s smog engines are like 130 or 140.
Remember those newer engines are rated net hp, vs. yours rated gross hp. Dress the newer engine up with your intake and carb, plug the air pump holes in the head and you won't be down much at all, if any. The camshaft events are different for smog but the lift and duration are very similar to your original cam. One of the newer pre magnum engines will also have roller lifters.
Retrofit a newer magnum with 230 net hp and you'll see a nice performance and maybe mileage bump as well. 2ยข
Robert
