General 4 link question

On another post from a year ago, someone posted pics of their 4 link and everyone said they did not have enough angle on their upper bars.  One person said that the bars need atleast 30 degrees.  Is this a good number?  What would the minimum be?  Also, is that measurement from bar to bar? 
I would go back to that post, but I can no longer find it.
 
Thanks in advance.

30° would be absolute minimum, I wouldnt go under 35° and 45° would be a lot better. If you cant get the angle you need, cut the bars up into a wishbone!

30 is a little too less. With all the links i have done i never go less then 40. I know its not a big difference, but it is. There is alot of stress from the force of the axle. I hope this helps you out man.

30 degrees minimum.If you go as wide as you can on the rear end, and as close as you can on the crossmember/frame you should be good. what kind of vehicle is it?

It is going on a 91 fullsize chevy. I am trying to run the upper and lowers to the same crossmember.  I currently have it modeled in 3D and I am going to be able to get 36 degrees.  Will I have any problems?

Also, how long are the bars that you guys have ran on your trucks?  I have alot of room to work and I am trying to figure how far back to put the crossmember that the link will be mounted to.