It is all relitive. You can make the bow any size you want width wise (within reason). So when you do your stack for weight, you over shoot a bit. I usually build 1 3/4" bow.. but they end up being 1 5/8" after final sanding and shaping. Most of my risers start off at 2" or 1 7/8", but then all the shaping and sanding gets it down to where it is needed.
So no worries.. just sand the riser sides down to meet the limbs.. it will be a nice looking fit.