anyone kno of a kit or any information on setting up a triangulated fourlink rear suspension on a 88-98 chevy c1500?  

http://www.minitruckinweb.com/tech/suspension/0708mt_1994_mitsubishi_mighty_max_four_link/index.html      

It is kinda basic but will show you the correct geometry on how to set up a 4-link. It was done using a Mitsu but the same principal for any truck.  

what would be differences if one would want to set a fourlink with coilovers instead of bags? I would like a stiffer ride and something that hooks well at the track  

the difference is where you establish your ride height and the relationship between it and the pinion angle of the rear end.

also, if you are looking for a truck that will hook up well at the race track then the postion of the bars is paramount. Max Fish of Bio Kustoms just penned a great article for Sport Truck's April issue that explains the different types of rear suspensions and what works best for each application.