You got an original dog in excellent condition already, in my opinion, this one can be keep in the current condition.
P.S. Those hot tricks option parts are very attractive!!
You may consider to buy the re-pro body shell from eBay. But I think your dog which is a SE version, so this roll bar should be original one.
BTW, i was so lucky to get an original Yokomo shell (early version, but not the one show in the photo) from eBay Germany last year.....