I run 60g as does Nick.
From the point of view of plain physics running the shocks on the rear of the wishbone will help free up the suspension movement making it more complient and consistent through it's travel, my shocks are always on the back.
The only expection to that is if I really NEED to move the weight forward in which case I run the shocks in the kit position.
This is my main concern with the big bores ... lots more weight there so will be a much bigger change moving them front to back
As for the question of diff settings it's all a matter of balance but I have always tried to run my diffs as free as is possible without them slipping, front slightly tigher than the rear. I personally still think this is the main benefit from a ball diff, can be right on the verge of slipping but still give good drive and free diff action at the same time ... with a geared diff it's one or the other (hence why I know a few Durango runners are using the Kyosho ball diffs in their cars
).
Nick will no doubt be along in a little while to describe the results of the huge amounts of testing he has done around diffs and slipper settings.