Unfortunately I don't, but it is really going to be different for every vehicle anyway. a standard would give you an idea, but it's going to depend on how broken in the springs are, shackle lenght like you already mentioned, even your bedload will make a difference. When the bed is unloaded, it is fairly light, so the springs are more likely to not flex as much and cause the truck to flex more at the front, since it is heavier due to the engine. Loaded, it'll flex better out back, due to the added resistance of the weight.
Your best bet IMO for setting your bumpstops is to load the bed with an approximate wheeling weight (cooler, tent, tools, etc. Just use your best estimate) and then flex it out to where your shocks are almost completely compressed. Then measure the distance, and mount your bumpstops accordingly. 
that totally makes sense BD. thanks for the info.. with that in mind I came up w/ a solution... I am going to fabricate an adjustable upper shock mount. that way once I figure out where to set the bump-stops I can easily move around the rear shocks dependind on what I'll be using my truck for. I will be posting picks and specs soon. I've got two jobs and a wife, and on my free time I work on 83' Yoda so bear with me I think the idea will work good..
