I just did this on my CJ7. Used a Waggy front instead of a Scout, but the principle is the same.
I decided to do a shackle reverse at the same time as I was outboarding the springs. I also am using waggy springs, but it really shouldn't make any difference in figuring the angles.
Here is what I did. I made a rear shackle hanger mount with a series of holes in it. So I could move the shackle hanger either direction to get my angles right. (This should also allow me to use different springs if I ever want to try something else.) With the front mounted solid and the rear where I "thought" it should be, I cycled the spring with a jack. In my case with the spring almost flat, i get about 45*. And at full droop maybe around 70 - 80*. At no point does it go past 90. So I "hope" I won't get that "over-center" bind or any shackle inversions.
It looks good on paper. And with the adjustable rear, if it is not right I can change it with a miniumum of BS.
Ask me again in a couple weeks after I have tried it on the trail and I may sing a different tune.
I posted some pics of the mock up I used to figure the angles on this thread.
Waggy Springs thread
AS far as the bar between the front hangers, I don't think it is necessary, but i think it will make it a little stronger and has the added bonus of giving you some beef in front of your steering box.
Hope this helps.