Cool boat. By the way you described it I thought it was gonna be a real shitangle.
I don't think anyone offers prefabbed interiors for this style boat. Too many variables like floor depth, width, etc. Look around here for anyone selling seat buckets that you can have upholstered.
I've seen very few jetboats run air filters. Usually it's just some type of scoop so water doesn't have a straight shot down through the carb. Look in here and in the v-drive forum, there are even a few members that will custom build one to suit you.
Oh yeah, metal flake rules!!!
http://www.***boat.com/image_center/...nator3-med.jpg
http://www.***boat.com/image_center/...nator4-med.jpg