I ride 40cm drops, that's why I got a 40cm Profile base bar for starters and it's just fine. It's just like road bars on the hoods.
I'm putting risers on a bike and am lost for a width. They are a 1.5" rise with no published angle for the back swept angle. Just some cheapo $25 bars to see if I like them. Same stem length but 6 degrees up instead of down. It makes for a comfortable upright position for me.
The bars were 65cm and far to wide for my liking. I cut 25mm off each end and they are much better but still too wide.
How much wider are your riser bars than your road bars?? I still need to cut some off but don't really want to inch up on it, unless that's what I need to do. If I'm still in the wide ballpark at 60cm I'd rather lob off a chunk then get closer rather than make a half dozen small cuts. Lazy.