Zedman,
Thanks for the very accurate summary of what's involved with this job. I did this on my own Avanti way back in 1993 (pre-digital photo era) and your report brought back a lot of memories! I remember that the roll-bar bolts were quite challenging as the only access was through the ashtray openings in the rear armrests. Removing the old, rusted troughs was one of the dirtiest jobs I've ever done - I recall filling an entire garbage can with rust!
Thankfully, this is a job that if done properly, only has to be done once. My hog troughs are still holding up well 31 years later. Good luck with the rest of your project.
Adam DeRosa