The problem is that the layout as displayed in OP doesn't accommodate proper typing method. Some would argue that standards exist for a reason.
The only way to keep both inverted-T arrow cluster and right Shift is to (a) reduce bottom-row offset and utilize non-standard 2u left Shift (see HHKB Pro JP or Rapoo KX) or (b) put the top arrow between symbols and the right Shift (which can be frustrating when typing), with weirdly aligned spacebar row. Neither is perfect.
Now, split spacebar. If the keyboard lacks 2.75u right Shift to accommodate the arrow cluster, the key and stabilizer can be arguably used in place of a standard 6.25u spacebar. Plenty of sets use the same profiles on the two lower rows, thus profiles wouldn't even be mismatched. 6.25-2.75=3.5… In other words, the remainder can be split between two 1.25u and one 1u, or one 1.5u and two 1u keys. That's easily doable with a standard keycap set.