Pacesetters have not been tried on an H-body as far as I know. Pacesetters are made down here in Phoenix, and one of their employees is in the local Grand Prix club. Echo SSEi is first in line to be test fitted for their smaller 3800 headers with either 1-5/8 or 1-1/2" primaries (I can't remember which), so whenever that happens he'll be able to report to the rest of the club. If you want the headers with 1-3/4" primaries, you can order them and be a guinea pig.
As far as the GenV blower idea... if you want to go that far, the option is there. However, there is still a lot of performance to be had in a GenIII M90, and your budget will probably dictate what you do. If you're not looking to go all-out, the GenIII will probably suffice with a pulley change. You always have the option of porting if you so desire.
To answer some of your other questions, Autolite 104s should be appropriate after the list of mods you describe. Are you running 606s or 605s right now? You may want to experiment with plugs, as you want the hottest spark possible without knock.
For a PCM, see if you can arrange a custom tune when everything is said and done. A DHP 1.0 is proven to be a solid PCM, but nothing is as good as having the computer tuned specifically for your application. An "off-the-shelf" tune will help, but will never get you spot-on like a custom tune. See what your budget allows when the time comes.
1997 SE w/SLE package
"White curse? I think it'* more like.... WHITE FURY!" - MyLittleBlackBird