Torsion Bars... Best Diameter for a Lowered Street / Autocross car?

Looking for feedback / suggestions on what diameter of torsion bar I should plan to purchase for my 71 Demon. The car will be sporting a 408 stroker and A833, and I plan to run either 17" or 18" wheel/tire combo for both street and track. I consider myself to be an "autocross hobbiest" vs an "enthusiast"... so probably 2-3 track events a year. Otherwise, it will be a fun street car that I want to sit low and handle well. I'm running SPC fully adjustable UCAs, QA1 adjustable strut rods, and factory (reinforced) LCAs. For what it's worth, I likely add on the Hotchkis front & rear sway bars also. I haven't decided on shocks yet...but will probably be either Hotchkis or QA1.

I'm looking at the torsion bar options through Firm Feel. Considering the 1.06, 1.12, and 1.18. I'm okay with a somewhat rough ride on the street considering it will be hard to avoid while being lowered... but not sure which of those 3 options to choose from.

So, let me know your recommendations. If you have photos of your ride with a specific setup, that's even better! And of course, if anyone has a used set they'd be interested in selling... let me know!

Thanks