Rather than the design I would be concerned that Velo-Orange Grand Cru headset comes in both JIS and ISO. A split crown race would work with sealed bearings, but my guess is they come in two sizes; JIS and ISO. Forcing an ISO over an JIS would split the race more than intended. I am also a bit confused by your LBS, I'm sure a call to Velo Orange would have resulted in a JIS crown race; it was quite common in the past as fork makers often made their forks JIS to make them more compatible. Also, if you can't find an LBS with a crown reamer, find a custom bike maker. I had a similar issue and Paul at Rocklobster pulled out a hand reamer and fixed the problem in less than a minute.