OP asked specifically how to make his car "corner". I believe your suggestion on ISO mounts etc more effects "handling", and I believe there is a subtle but important distinction between the two.
How to corner: turn steering wheel in direction of turn
If car continues to move straight, slow down until car makes turn
With any car, it starts at the tires. Tires determine the limit of grip. Suspension is a system that makes the most of the limit of grip in regards to the weight and rigidity of the chassis.
Thus, the next consideration is the chassis. How heavy and stiff the chassis is will determine the rest of the suspension package.
In regards to the 72 B-body, there are multiple choices for this car with Firm Feel and Hotchkis being my favorites. The 73 B-body there is really only Firm Feel. In regards to the late B: The rubber chassis bushings need to be replaced with poly or better yet solid. If you think the 72 b-body has too much road noise, then poly mounts are the choice for you. Otherwise, the main weakness in the 73 B is the front frame rails really having no support other than the very heavy k-member bolted to it.
