KBT Pure (not pro) will need the base common set, one modifiers set either text, or icons, and a 6.25 space bar. But, the only way to get the right shift 1.75u is to get also the pro modifiers set, again in either text, or icons.
1 common set
1 modifiers set
1 pro modifiers set (To get the short right shift)
1 space bar 6.25u
I am not sure, but after a second inspection of the modifer set it appears it has a 1.75u already? or is it 1.25u?, let Matt confirm that. If that were the case you can do it with only the base, the mods and the space bar.