i had my old chassis galved after replacing all the out riggers, that could be a bit cheaper to do, i stripped all the body work off panel by panel and refurbished each part as it went back on (painstaking but good end result), or you could leave the body complete and just remove the fixing bolts and lift the body off in one lump. As for stainless bolts any bolt supplier should be able to supply these although i wouldnt bother, if you assemble everything with lots of copper grease the bolts will stay in good shape for years and years, the only reason there hard to get off now is the fact they werent assemble with any grease. there are bolts on mine that came off piece of cake because of an oil leak on the engine had kept the water out.
hope this helps a little.