Engine Smoking? Minor? Do you mean using/burning oil and you are seeing bluish smoke from the exhaust? Or oil seepage from something like valve cover gaskets that is landing on exhaust and smoking.
I don't think using could ever a minor issue on a Land Rover. But, I will admit I don't have much experience with a Land Rover specifically. Assuming you mean using oil and that you are comfortable working on it, do you mean you can rebuild the engine? I would think that would make the purchase not worth it. Yes, you will save tons of money on labor. But, parts to rebuild a Land Rover are going to be prohibitively expensive, aren't they?
To answer your question directly, I have never imported a car. But, I researched it several years ago. The modifications that have to be made aren't that big of a deal and there is some extensive red tape to get through. I was comfortable with all that. The thing that stopped me was the cost of shipping. It cost so much, it didn't make economic sense for me.
The seller isn't specific on the smell/look of the smoke but has reason to believe it is fuel related might be a leak hitting a manifold.
I've assisted in a few engine rebuilds/swaps/etc in the past so I have enough exposure to feel comfortable jumping in. That, and having a father that owned/operated a custom engine machining and import shop gives me access to enough knowledge/resources haha. My understanding is that the V-8sin these models were used heavily in the 80s and early 90s so sourcing parts shouldn't be too bad in the event I would need to. However, if it is the diesel model (which I cannot recall at the moment) that would make things a little tricker as far as access to certain parts.
What modifications were you asked to do? With 25 years or older cars there's not too many hoops to jump through, unless its state specific regulations that are above and beyond. However, if you were talking under 25 years then I agree, much more rep tape especially with crash safety/emissions controls.