Should I get a 360 motor/tranny

There are several different diameter/spring rate torsion bars. I wouldn't be at all surprised if a loaded slant car had a 8.25 rear and/or the same size/number torsion bars as some 318 baer model cars had. The slant does throw its weight harder to the right side bar.
Any torsion bar will hold the car up if the adjust bolts are cranked up high enough. The difference is in the spring rate and handling. Think a torsion bar can break ? It is possible and dangerous loss of control is likely. The very largest bars for big block cars may be too stiff for some. I guess if you want it the way the factory built it you would first need to identify the bars you have and compare them to what factory charts list for your build.