Find a spoke shave at a flea market. Tune and sharpen it.Cut the flare with a jigsaw or bowsaw and Plane the curve to the line with the spokeshave.
Or 3M #77 spray glue 60 grit paper on an 1 1/4" dowel. Shouldn't take much longer than the spokeshave. But it's such a satisfying tool to use.
I mostly use my Record convex one to smooth out speaker cut-outs after I've managed to have that freakin' dimple cut-out when the hole jig slips as the cut-out is completed.