Jamie,

we recently removed the sound deadning material out of Rob's chassis. It takes about a day total to do it properly. you'll need about $30 in dry ice from a local dry ice / carbon dioxide supplier, cover the entire floor with it. the chassis will creak and groan, and tap everything with a hammer. entire 1' x 1' sections will just pull right off. the hard part is getting it literally out of the car, and out of all the nooks and crannies. you need a shop vac, a brush, and a dust pan.
after that about 3-4 cans of brake cleaner and a wire brush to scour the whole thing, as well as scuff it up for primer and base then clear.

it looked like you used a heat gun, but what was your technique?

looking good! be sure to remove the other bracing and stupid shit on the bottom side of the chassis, as well as pressure wash 90% of the crap off of the bottom of it. You'd be surprised how heavy dirt is!