Rather than block placement, I think a more useful (and simpler, since it doesn't require a "current block" selector) feature would be to have an option to refill stacks (or just do it by default).

For example, if cobblestone is one of the items in pocket storage, and the player also has cobblestone in their inventory, then try to keep each cobble stack topped off at 64 (or whatever the max stack size is for that item) by extracting items from pocket storage -- but only top up existing stacks, don't add new stacks.

It must either leave a minimum of one item in the pocket storage or allow that slot to go to zero without forgetting which item was in that slot.

This allows the player to start with a clean inventory, pull one stack of something out of pocket storage, and then use it to build as much as they want -- as they place each block the stack in their hand gets topped off back to 64 (until they run out of items in pocket storage), and if they break the blocks then they get sucked back into the pocket storage automatically.

This would take this mod from B tier to S+

Seconding this request