Rear shock mounting is always a compromise unless you are willing to have them through the bed. As close to vertical as possible is best for handling but makes it hard to get all your articulation without the shock being the limiting factor. I have been fooling with shock mounting for years and I have found a few things based on my experiences...
You will want to tend at first thought to go for max extension (droop) at the sacrifice of comression (stuff). Don't do it! I have found that my setups work and articulate much better in the real world with functioning bump stops that come into play a good inch or two before the shock bottoms out. Of course you have to alter things depending on tires rubbing too hard, ride height and such but this is something I've found out the hard way over the years. If your shocks are your bump stops you will eat up shocks as well and possibly even break shock mounts. It they top out a bit at extreme full droop it doesn't seem to by quite as destructive and you can also run limit straps to slow things down in the last inch or two to deal with that.
Everybody does the A style with the shocks like 1" apart on the top these days. I'm not saying that's bad for everybody, it just depends on weather you mind having a floppy rolly ride that's just good on the trail, or weather you expect yout rig to handle better that a garbage truck on the road. As far as engineering goes this is leaving alot of handling and on road/high speed stability on the table and you don't have to have the shocks leaned over quite that far to get all your articulation. Mounted A style with the shocks really close together on top the damping is hampered from the leverage and body roll is far worse than it has to be. The further you lay a shock over in relation to the vertical travel the less damping it can do. If possible I would have my shocks nearly vertical and outside the framerail but there isn't enough room between my tires and frame. My favorite I've tried so far is two shocks mounted to the rear of the axle angled back on top //, but vertical as you look at it from the rear )-l-o-l-( and scooted in about 1-2" more than stock. This configuration has been the best I've had at spliting the difference between articulation and handing and it fights axle wrap too, especially if you have gas charged shocks.
On my 4Runner I couldn't do this two the rear setup because I have a 35" spare up under there that's in the way so instead I mimicked the 1st gen configuration as best I could. For this one just look under a 79-83 pickup. That is still the A style mounting but with the tops of the shocks 8-10" apart instead of nearly touching like everybody seems to be doing these days. I am running chevy 63" springs in the rear and they have tons of flex and my 12" stroke shocks are still not my limiting factor. This does not handle cornering when loaded as well as the two the the rear, more vertical setup, but it is working better than the A style with the shocks nearly touching at the top.
I still want to try to push my shocks further out and at less of an angle, but I will have to mess around with it for a while because of exhaust and other space problems. I was thinking of using KYB gas adjust shocks because they are a decent monotube but more skinny so they might fit in the limites space better. I have ran them on a few rigs over the years and have never had one fail and I think the valving is better than the bilstiens I've ran even though they don't look as cool.
Here is what I ended up with on my 4Runner and I think it's still too much of an angle and slightly too far in to the middle of the axle. You can also see that my bumpstops are not functional in this photo
. The second photo is of the "two the the rear" configuration that worked alot better for handling and still worked great for articulation...
