Speedman,
You should check out Savitske Classic and Custom at
https://scandc.com/ Mark Savitske is the owner and author of his book entitled "How To Make Your Muscle Car Handle".
I also have an '87 El Camino and wanted the handling characteristics that you've described in the first paragraph of this posting. Earlier this year, I bit the bullet and dropped a chunk of change to get SC&C's Touring Plus package shipped to me in Hawaii. Basically, SC&C has done all the research, testing, and packaging to offer all of the necessary parts to transform your G body suspension.
Although the parts arrived almost 9 months ago, I have not driven it yet. I am in the process of building a replacement chassis with all of these performance enhancements. In addition to these suspension upgrades, I am installing front and rear brakes from a 2000 Blazer. My drive train will include a rebuilt semi-mod 350, Bowties Overdrive 2004r transmission, and '87 GN 8.5 in rear end. The 350 will have a balanced forged crankshaft, Comp hydraulic Cam, aluminum heads, headers with Pypes exhaust, and old school dual quads. This will be my wife's ride!