Re: SOA issues :(
You can run a CV shaft with a slipyoke if you have a slipyoke that isn't sloppy and has lots of spline length. Jesse at HighAngle makes 'em. CV isn't cheap.
When you switch to CV you have to make sure that the driveshaft is in parallel with the pinion or else you'll have vibration. I'd see about getting the pinion in line with the crankshaft because CV shafts aren't cheap. Common practice on SWB SFA Chevy vehicles is to drop the transfercase an inch.
As far as making the shockmounts hang below the axle, it's usually so they can run a longer body shock.