do you have two cameras? You could shoot them side by side which would make post a lot easier. But isn’t that what pre-planning is all about?
The shutter speed for 60fps should be 1/2x so 1/120th is fine, then when you decimate, slow down, or whatever, to 24, it will maintain the same blurryness factor. Now if your final product is 24fps, all your non-slowed down 60fps will have to go through optical software such as timewarp, twixtor, compressor, magic bullet, terranex, etc. to not be stuttery.