I'm interested in hearing from anyone that has swaped out their small block for a big block in an existing cobra. Assuming that your manufacture will easily accept a BB, What issues are the biggest herdle? Has anyone ever just taken there car to the engine builder of his/her choice and said "I want more! take this out and put this in!!"

If so, what was the app. cost?
I realize there's several engine options and the cost is directly related, but just curious of how many owners do engine swaps compared to selling there existing car and buy a different one.