When you change the thermostat, be sure to get a new o-ring and gasket. I think both of those parts are less than a dollar. Your gonna need a pan under the engine to catch coolant that will leak when you unbolt your t-stat housing too.
For weight reduction at the track, you can take out ps seat, rear seat, door panels, rear speakers, all carpet padding and basically anything in the trunk, windsheild wiper reservoir, wipers, drop the exhaust, have 1/4 tank of gas or less, and other trim pieces.
all that stuff is alot of work but it should all add up.