Help needed: SuperSix Evo Gen4 w/ CRW Works HB01

Hi, i recently ordered a CRW Works HB01 integrated handlebar and wanted to replace my current handlebar on my supersix with it. However, after unmounting the current handlebar and stem, i realized that it is 1 1/8th and the hb01 has 1 1/4. anyone with some experience? is it fine to use a shim? if so, any suggestions?