The problem with chroming a aluminum valve cover is not many places have the ability or the proper chemicals to do the job correctly. I have a gentleman who has looked over my extra set of 12 valve stuff recently to try to determine if they could be done in his shop and his answer was this...
"Yes,I can do them,but,how long they would last is another story. If the aluminum is not properly prepped and cleaned all it will do is end up bubbling up the chrome. Keep in mind how porous aluminum is and how many minuscule particles of dirt become trapped and how hard it is to prep. Not many people want to spend the amount of money it would take us to prep the material to chrome which is where most of the incurred cost would be. I could anodize alot more parts for the same cost for the owner than chroming one piece like that. "
I have seen what happens to the Cummins set for the 12 valve after a long winter here in PA with chemical salt. Once that crap gets sprayed on it what a mess to keep nice forever,rust constantly popping up. Polishing or anodizing is the deal and would provide a longer lasting look... ... ... Andy