Tip: When determining a time limit, remember that players won't be as familiar with the level as you are. If you normally complete the level with the timer around 100, others might run out of time on their first try.
This definitely a creative idea for a block which could be used in quite a lot of places. You could have made it a little more user friendly, at least by adding more defines.
During the moderation, I added the sa-1 tag since the blocks themselves are actually SA-1 hybrids and I included an SA-1 compatible version of GPS's spawn_item_sprite routine. I added assertions to the Map16 variants of the block to make them impossible to insert without first patching the Bounce Block Unrestrictor patch.