Let's say your car weighs 3000lbs and has a weight balance of 50/50 (which it doesn't. . .it weighs more and has a F/R% much worse, so this example is possibly the lightest case scenario).
Anyway, in our example the front axle is holding up 1500lbs total, or 750lbs per side.
the Shockwave mounts in the OE shock location, which is roughly in the center of the OE lower control arm. Therefore, the front has a motion ratio of 2:1 (the shock/Shockwave moves 1 inch when the wheel/tire moves 2 inches. Also, the shock/Shockwave carries twice the load as the wheel/tire). So the shock/Shockwave has to be able to lift 1500lbs total in our example.
The 7000 Series Shockwave is capable of lifting 780lbs at 100psi (http://www.ridetech.com/images/categ...harts/7000.jpg
If you place the Shockwave in there by itself it won't lift the front of the car.
Now, say the torsion bar provides a spring rate of 500lbs/in, and you compress it 2 inches (minimum distance of typical vehicle compression).
With the torsion bar and the Shockwave combined they will lift 1780lbs, which is enough to lift the front end.
Will you be able to "slam it"? That depends on what you mean by "slam it". With this setup you'd be able to lower the vehicle as low as it would go if you disconnected the torsion bar all together. How low is that? I don't have the foggiest as I've never dropped a 66 Valiant. However, my guess is that it would look extremely low. . .low enough you couldn't drive it, but not so low that it drug anything on the ground, so it would still roll.
The skill level required to accomplish this is a bit on the higher end. . .you'd have to be able to source a tubular upper arm with the proper geometry (or build one), and possibly build a set of spacers to fit the Shockwave to the OE lower control arm.
It's not exactly building a custom one-off frame. . .but it's not sticking on some cool flame and tribal graphics from the local auto parts store either.