My response would be along the lines of "dear sir the person who made that last pie was fired. I have taken over her business, and NO I do not bake pies."
HAHAHA.... this cracks me up!!!
I would be wary of customers like this who, on several levels, give you specific instructions. I would not get involved. He's got some personal issues and you don't need to find out what they are.
It's one thing to have a change of heart, but are you prepared to continue to make pies and have him give you detailed instructions from now on? Guarantee he is going to be back and he is NOT going to understand why you won't do them anymore when you've made pie (or now pies) for him already.
I would have said no... if someone wants to order a pie from you, it should be YOUR pie (your recipe)... having someone send you a full recipe with instructions and 'tips' on how to make a good pie would put me off. I would point out that they have all the instructions and tips... they should give it a try themselves. That, or do what others have suggestion and price it rather high. If he says okay, go for it. At least you're getting a decent profit.