Also keep in mind the fact these old bars have work hardened after 45 years. I'd like to think the newer bars have better metallurgy..
Now as far as quickening of spring rates, I'm gonna agree with wjajr, and add that it depends on the relationship between the weight of your front end, and the spring rate, so it's very elusive and depends on on a lot of variables so you can't say "it feels like this.". It's trial and error.
The opinion is: 1" seems to be a good compromise, and a safe bet between hard and soft.
I'd rock the 1" without a thought about getting scientific or wanting to be politically correct with it. Seems to be a pretty popular size, and the prices reflect that, which I see as a bonus.
Everyone has the same hesitation with "1 bars: 'Oh, that sounds too stiff!' then they install them and say they are 'Firm, embracing, modern (add positive adjective here) but not harsh, I love them!' ...and that's with small blocks. As you can imagine, big blocks would be even more cushy.
"Where you have a big block I wouldnt hesitate using a 1.00 or thicker bar, in conjunction with a good anti sway bar, and a Firm Feel steering gear; youll be happy. Also this would be a good time to install new front end bushings if yours are getting on the worn side." -- wjajr
That's good advice.
Here is the link to the bar's I have:
http://www.justsuspension.com/pro-touring-torsion-bars.html
Also, it might be a good idea to hop up on energy suspension and grab some polyurethane dust boots, if you don't already have replacements. If you have fitment issues, stick the poly boots in the microwave, or boiling water for a few seconds, should loosen then right up.
Heres a link:
http://www.energysuspensionparts.com/proddetail.asp?prod=41701&PARTNER=gbase
Good luck!
