Going from memory, I think the front suspension on that frame is about right to fit under a lowered truck, meaning its a touch narrow at stock ride height.
Check the width of the rear axle. If its the same as a Monte Carlo of the same year, and it may be, its really too narrow unless you tub the bed.
There is a section in one of Tex Smith's books about narrowing a frame similiar to what you are probably thinking. If you haven't seen it you might want to look for a copy of
How to Build Custom Cars. That link is to Amazon but you can probably find one on eBay cheap.
