I think you are good as long as you are under 75% fill in that space. As you said in your post.
312.8 Switch and Overcurrent Device Enclosures with Splices, Taps, and Feed-Through Conductors. The wiring space of enclosures for switches or overcurrent devices shall be permitted for conductors feeding through, spliced, or tapping off to other enclosures, switches, or overcurrent devices where all of the following conditions are met:
(1) The total of all conductors installed at any cross section of the wiring space does not exceed 40 percent of the cross-sectional area of that space.
(2) The total area of all conductors, splices, and taps in-stalled at any cross section of the wiring space does not exceed 75 percent of the cross-sectional area of that space.
(3) A warning label is applied to the enclosure that identi-fies the closest disconnecting means for any feed-through conductors.
The terminal blocks take up more space than splices. That would be my only concern. You can stagger splices. Not so with a terminal blocks. It makes a neater installation but takes up more space.
Good Luck!