With the malt substitution you could go either with or without the 1# crystal. Without it would look closer to the original, and taste pretty close... but lack the bit of depth of character the crystal gives... OR you could use the crystal and it would look bit darker and be ever so slightly sweeter and have more malt flavor.
Either way it isn't going to be EXACTLY the same beer as the original recipe, but will be a good beer whichever way you choose to go.
For my taste, I would use the crystal. In fact, with the Munton and Fison Amber malt extract this becomes the recipe that I have given to a number of beginning brewers and they were all very happy with the outcome.