R3 PgUp, R4 PgDn and extra 2.25u Shift in the base kit, please. Those keys are more common that the 2u Shift, stepped 1.75 Control and 1.5u Supers that you have in there now. Also, if you want to have 1.5u Supers for Mac and true HHKB layouts, you should add a second 1u Alt.
You also need to add a white R1 Home and white R1 PgUp if you want to cover 65%/75%/1800 layouts without mixing colors in the right column or above the numpad. Instead of doing that, I would just change all of the current 65%/75%/1800 keys to black (that includes: R1 Delete, End, PgDn; R2 PgUp; R3 PgDn; R4 End, Fn) and then just add a white R4 1u Fn for 60%s. This also lets you add R3 PgUp, R4 PgDn without needing to add a white R2 Delete.