Rear suspension questions

[Spray-Bomb]

Hey guys, I recently picked up a disc rear out of a Caddy & it has mounts for a triangulated 4 link cast onto it

My question is, would I be better off building new arms for the rear axle & make mounting points on my frame to use the 4 link
Or, just unbolt the disc brakes & weld on some trailing arm perches on a 73 rear I have ???

I know the 4 link is a lot more work, but would there be any real advantage by using it ???
The truck is bagged & will have a 3" or 4" notch (at least to start with)

the other thing is, if I use the 4 link set up do I need to build the links the same length as what was under the caddy, or can I make them longer ???

Thanks, Matt