The Cobra track loc 31 spline diff with the carbon fiber clutches works well up to 600 or 700whp and they are pretty affordable, around $250.
For best straight line performance run a synthetic oil with no friction modifier, the friction modifier makes the clutches slip more, not less and if you use a synthetic you don't need it.
Go with some forged 31 spline axles, I got the Mosers and they are working well, replace all the bearings and have the axle tubes welded to the center section and you are good to go.
The center section on 8.8's is cast steel, not cast iron so its an easy weld with a a tig or mig machine, no fancy nickel filler rod is needed.
If you take your time and do short welds spaced 180 degrees apart it won't warp the tubes out of alignment but if you are worried about that take it to a shop that has a jig for it.
The aftermarket axles allow you to put ABS rings on but its a pain, I'd go with the get it hotter than hell method to put them on, I cracked one trying to put it on without heating it.
With all that trouble, think hard about if you really want to stick with the 3.27's or go to lower gears while its all apart, the gears are pretty cheap, the Motorcraft ones are recommended as usually the same pinion shim works, making the installation faster.
With the overdrive gears in both the manual and auto trans in our cars a 3.73 gear is still real streetable and you'll get a nice kick in the pants out of that gear.
If you are going to be drag racing I'd also go with a Yukon solid spacer kit instead of a crush sleeve (tends to loosen on hard hits), the Yukon spacers are better made than the Ratech ones.
2.1 KB 12psi/2600 MAF/75mm Accufab TB
Silverfox VB/Circle D 3400 CV/Steeda LCA's+Subs
Control Boost from ControlBoost.com