There are cams available for 3800 II - noth NA and supercharged. They are offered for the Grand Prix but will fit the Bonneville (same engine).
Intense-racing makes and sells cams for both L36(3800 NA) and L67 (3800SC). They also have rockers/pushrods.
Scott Cook has the cam in his 2000 Bonneville SSEI which runs the 1/4 in the 11s. He is very knowledgable and helpful. He may be able figure out if you can use his cams in a 3800Series I.
Thrasher makes a CAM for the 3800SC.
SLP also offers roller rockers with lightweight pushrods for both supercharge and NA engines.