Threaded to Threadless - Minimizing Ugliness

I want to do threaded to threadless stem conversion. I want to try the Jone-H bar on my 1989 Mariposa touring bike. If I get ambitious I'll also swap out the 700c wheels for fatter 650B's. Trouble is, over the years I've been raising the stem to compensate for my ageing, decrepit backbone. Acquired...