There are a couple of 'gotchas' with 1" swaybars. First, solid bars are stiff enough that the steel frame crossmember on the rear of some cars will flex along with the bars! We tried a 1" bar on Judy's street car and a GR-4 clone w/10" & 13" wide wheels & tires, on a skid pad many years ago. The 0.865" OD GTS rear bar actually worked better on both. So you don't get the full effect such a big solid bar should give, and if you drive hard, the big bar over time may actually crack spot-welds or the 10mm holding studs.
As Marlin said, hollow bars are less than half the wt of solid bars. A hollow 1" bar made of 4130 x 0.120" wall tubing is also 32% less stiff than a solid 1" bar, and apparently does not quite flex the stock spot-welded Pantera rear frame. Seam-welding the whole rear subframe is a good idea and cures the flex problem. Hollow bars also have problems; welding limiter washers on WILL eventually crack high-carbon bars at the welds- even tack-welds. Use clamp-on limiters with all hollow bars. McMasters catalogue carries such things, or they are easy to make from scratch. I made a set of hollow 4130 bars for our car in 2007 with clamp-on limiters & everything is still working fine. Note with custom bars front or rear, if they don't fit perfectly on your car, try swapping the bar end-for-end. Many Pantera subframes are now asymmetric after 45+ years of hard driving, and a custom bar (which itself may not be perfect) might fit better one way than the other.
Using polyurethane bushings on the ends of big bars may crack the welded clamp piece on stock lower a-arms, as poly does not have enough 'give'. Instead, use stock rubber or (better) sphere-balls on the outer ends of ALL Pantera swaybars. Poly works fine in the centers as pivot bushings but are just too stiff for the ends of either front or rear bars. With sphere-balls you can actually feel them working! All this stuff- including simple calculations for front & rear swaybar stiffnesses are in a POCA Tech article, dated Jan 2008 and available on the POCA Website archives.