This attorney will never get that Land Rover in country, and here is why; The moment the original owner swapped in a newer engine, he made it impossible. The writing is very clear on this - If it was an original vehicle, it is over 25 years old, and it can come into the USA. Once he swapped out the engine, now he has to EPA certify the engine, as the vehicle is no longer covered under the 25 year exemption. This is a losing battle, as the guidelines, actual instructions if you will, are painfully clear and not open to interpretation.
I only write this because no "attorney" has any more smarts, power, or tricks than you are I do. It is in black and white, literally, how to legally import an L79, any car for that matter. It is perfectly, 100% clear on how to get it done, anyone can do it. You could do it yourself. All you have to do is read, there is no magic to it.
ANY vehicle on the planet can be done if you throw enough money at it. ANY vehicle. Some just are not worth throwing the money at.
Notice I did NOT say it is "inexpensive" or "easy". It is clear how to do it. If you do not wish to put the time into learning how, that keeps people like Steve, like myself, in beer money.