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.
Works fine. Note however that by default, !TickRate could only have $01,$03,$07,$0F,$1F,$3F,$7F and $FF as values. I changed this. You had also missed a replacement with !TickRate in the GFX routine. I have fixed both since they are minor issues.