I think, and from my understanding, all small block torsion bars are the same at .870, the next size up are 383 big block bars at .890... It would probably be best to get those 1.0" bars from just suspension like you mentioned...
Nope, not all small block bars are the same. I would get the 1" bars bu I can't justify getting them for a slant six daily driver that I may end up selling in a few years. The 340 bars worked out great on my 73 scamp as a daily driver. I am also planing on lowering the dart about 2" and I still want a good amount of travel out of the suspension.