Not bad choices at all for the flywheel and clutch kit, you can get the alignment tool at a local parts store for less than Summit had listed on the one link you posted, I think I paid less than $2 for mine when I got it.
You might also want to see if you can get the driveshafts for that specific transmission / transfer case combination also, I know they might be different than what you already have, I just don't know by how much.
I was lucky enough to have at least 4 other 2-piece driveshafts in parts storage and could get what I needed just by measuring and swapping the front half when I did my auto to manual transmission swap.
I don't use the 6.55 geared first gear much when starting out in the Suburban, and have actually started out in 3rd gear while pulling my snowplow truck out of where it had been sitting for over 2 years while I was away from home working.
I'm thinking about swapping the suspension under the Suburban from 2 wheel drive to 4 wheel drive next summer, as I have started driving it again and this 9 inches of snow and a driveway on a hill make it a little more difficult to get out when I need to.