That car must be twisting like a bastard. Have you done any bracing/chassis mods?
To the OP, I believe the most effective and inexpensive route would include a heim joint attaching to the motor (the schumacher/mancini straps have them). Mancini's torque strap is nice, but could be made for $20-25. Here's a pic I found on a member's thread, but it only shows the upper strap with the heim.
You can make this at home with some threaded rod to screw the heim joint in. Because the heim rotates freely within the joint, you can dial in your slack within a milimeter if you want.