How big are the pieces? Without that, it's pretty tough to answer your question. On the other hand, I'm sure you could make it fit, simply by making a smaller block.
Looking at the instructions for a 24" block, you need four 3 7/8" strips (from a fat quarter, 21" wide - they use 2 42" WOF strips), and 2 3 1/2" strips of colour 3. Everything else uses less. That totals about 16" + 7" = 23". So your FQ of colour 3 will be slightly too small. The other colours would be fine.