I don't know about the handling......yet!
I have installed an AlterKtion and the 4 link from Bill at RMS. I have also installes the entire body stiffening kit from XV, all in a 70 GTX.
I have also installed the 5.7 and the w5a580 transmission from a wrecked o7 Charger in this car.
I still have some bodywork, paint,interior stuff to do . By my calculations I think this car will weigh somewhere around 3800 lbs when it is all done.
You can see progress pics on Moparts member project and Survivors forum "70GTX-5.7 Hemi Build" thread
or even better pics at
www.forbbodiesonly.com 1966-1970 Mopars forum "b body stiffening" thread.
This does not answer your question about handling but it may give you something to think about as far as effort is concerned.
Good luck on the project whichever way you decide to go!