Does anyknow the engine weight of the 3800 NA and */C and the Northstar. My reason for asking, is that Eibach makes a Pro-kit lowering springs for the Cadillac Deville.
They are 1.5 and 1.8 drop springs. My only concren is that the engine weight is so different that in the front end, it actually might not lower the car but give it a stiffer spring rate and raise it. Since the cars are the same platform....... I do belive I might have finally found a lowering spring for the 00-05 bonnevilles.

I think knowing total car weight and weight bias (front/rear) would be more indicative of what the springs will do.

Is the Northstar all aluminum? The all aluminum 5.3 V8 in my Grand Prix GXP actually weighs less than an L67. But as has been said, you really need to look at total front and rear axle weights.