ok I already searched this and found all kinds of discussion on roll center ect. all fine in theory but I need it to translate to reality.
I want to run sa-link setups front and rear on my fullsize chev, I understand the concepts in abstract, that is to say I could build it but I only want to do it once so need to hear from people who have already made the mistakes and who understand how to make correct geometry.
the links themselves i would like to build identical front and rear top and bottom for simplicity, they can be 48 inches long with no problems fitting them, I am waffling between 1/4 elliptic and coils from an f-150. shocks will be dual rs5000's mounted on the links someplace to match the travel.
my primary interest in this is to minimize my approach and departure angles and maintain the flex and ride quality I have with 88-up rear chev springs at both ends.
can anyone tell me how to figure out the ideal mounting positions and angles for this?

i dont think you can get a a high roll axis with SA design in anything but a buggy.
also think the front axis and rear axis would be hard to get working together.
do you want front and rear roll axis slope to be the same slope or opposite slope with an SA?
tough to get links under the engine

I eyeballed the linkage space under the engine and I'm fairly sure I can get it to fit if I reroute the exaust, I run about 6 inches lift and that has made some space, the front upper may need a few bends to clear everything but thats not a big deal.
define please "high roll axis" why do I want it and how is it acheived?

With out more detailed info about your set up I can't give you any specific answers to your suspension set up, but I will answer some of your questions. The roll axis is the line between the front and rear roll centers. The distance between the roll axis and the center of gravity is the lever arm that rolls the body with respect to the axles when there is a lateral load on the vehicle (ie off camber driving and cornering). The shorter this distance is the less roll you will have, but you lose cornering force at the tires as you raise the roll axis. So for every unique suspension set up there is a unique roll center height and you need to find the balance that you want between off road and on road use. If in doubt try and stick it some where in the middle. The slope of the roll axis effects the oversteer and understeer of the vehicle. If the axis slope down torwards the front of the vehicle the car will understeer (push) and if it slopes down torwards the rear of the vehicle it will oversteer (be loose). If it is horizontal the vehicle will be balances.

As for the link angles try and keep them as horizontal as possible. This gives you more up and down travel and less front to rear motion when you cycle the suspension. If you want to know the best suspension angles I would need a whole lot more information on you specific vehicle. I hope all this helps. If you want more info PM me.