Adding to the record, despite a feature thread elsewhere, here's some detail on the LS1 conversion.
GM changed the backing plates from the 4-bolt trapezoidal pattern that dated back to the 1960s, went with the funky two-small-bolts and shoe-pivot-thingie with the godawful clip holding the brake cylinder in place. The irony of this conversion is that GM elected to reuse the identical pattern (with metric bolts) for the disc brake backing plates in the S10 and F-body. Bless the lazy engineer. Wonder if they anticipated we'd raid the parts-donor era of F-bodies to retrofit the G-bodies?
So, the scary part - cutting down the brake tab on the axle ends. Commitment - no going back. There is just enough plate to cut at the very bottom edge of the big hole for the wheel cylinder.
The next trick is to drill out the holes. It is necessary to swap the left and right LS1 backing plates so that the calipers are toward the rear so they don't hit the frame when the suspension shifts up. The good news is that even I can't screw up drilling out the holes, because the two lower holes GM used to fasten the backing plates line up perfectly with the two lower holes in the trapezoid pattern. Thanks, GM engineer who specified two of my pilot holes!
The next task is to set up the calipers so that they are centered on the rotors. I chose to make shims for the backing plates. Drill, jigway and files (and safety glasses - pulled a sliver out of my cheek - easier than an eyeball).
Next, I had to figure out the brake lines and hoses. Note that GM changed the line end to a 'bubble' flare. There are conversion couplers you can buy at the parts store, but the donor Camaro lines were still clean, so I just rebent them for the G-body axle configuration. I needed something to fasten the hose ends, so I tracked down these Allstar circle track brake hose tabs and filed slots in the right spots for the hose index.
The next task was making brackets for the parking brake cables. A truly excellent Forum member made patterns and provided them with a full description of the conversion. I replicated his work with a few updates. The last photo was his - I had to shorten mine to clear the tires I planned to use.
Since these were junkyard parts from a 2000 Camaro, lots of scrubbing, sanding and painting required. Use VHT or other thermal-rated paint if you plan on using these calipers for real.
I am using 16x8 IROC Camaro rims, and they clear with no issues.