Gotta watch those Novas though, some of them were really narrow. I have one and I have to get some silly offset wheels to get the tires in the right place.
As for 12 bolts, you can find them in any late 60's SS version Gm muscle car; Impalas, Chevelles, Camaros, etc. Novas from the 70's had 'em too.
You don't really need a 12 bolt under your truck unless you plan to do some real drag racing or put sill ypower to the ground. My 52 is so light in the rear I can light the tires anytime I want to. This is hard on tires but not too taxing on the rear end!