Well, I'm not very into the "metagame" or whatever, but here's my opinion.
His original plan was to be a physical wall, right? Well, I say keep it. The Sp Def bonus will help slightly in his walling, albeit his physical walling will be slightly hindered. For some reason, I'm having a hard time putting this in words =/
Put the EVs the way you had originally planned. The Sp Def bonus can only help. With it, he might survive a special attack, gah! Why can I not find the words? I have it all worked out in my head, but I just can't type it > : (
I'm having a mental block...
Okay, I think I got it. His defense won't be as good as you planned, but it will still be good. The Sp Def bonus can't hinder you. There, I said it, I'm done. I hope you get the jist of what I'm trying to say. Sorry :blush: