1965 MMP's Barracuda Hemi swap! The Ever Changing Build

So sitting in my garage last night after a freaking long *** day contemplating the 4 link build when I got a really dumb idea of going IRS, So then my day turned into a long *** night of researching the possibility of swapping in a Merc or Bimmer rear cradle than I found for relatively cheap ford and charger rear setups.
Everything seem much to wide to be usable, then I stumbled on to the tried and true jag setups, found one out of a xjs v12 local for not a bad price, but now I'm back onto thinking of just building the tri 4 link.... ugh Looking for guidance or feed back, I guess cause I'm torn on the subject at the moment.
I also need to figure out what spring rate will be needed on each corner.