Still can't find rates of the tahoes. But if it's bouncy unloaded, sounds like you don't have enough shock.
Somewhere I dug up some part numbers that should work well with a 750 front and like the 239lbs rears. Was from a dodge truck application that uses those springs. Got that info at work.
You may want to try the tahoe shocks. But would need to modify the ends. Think you could just press out the top sleeve and press in a stock type T bolt from an old set. Bottoms may work just without the sleave.