Well speaking from experience I can tell you that the rules vary greatly. Yes we have federal laws and rules and then we have the state laws and rules as well as the interpretations of those laws and rules. Here is what I can tell you for sure:
1. varies greatly from state to state, California is the hardest and florida is probably the easiest.
2. What works one day might not work the next day
3. What is ok in one state may not be ok in another
4. you are far better off finding what you want already here than trying to bring one in yourself
I have had Cruisers from Dubai, Czech Republic, Japan, Canada, Honduras, Australia, and Saudi Arabia.
In fact I have a 1997 Toyota Land Cruiser HZJ75 Troopy from Australia Titled and registrered in California. I did nothing special to title and register it in California other than walk into the DMV and register and title it, honesty that was the luckiest day I had
I bought it from FL and it had a Florida Title and Registration, I went into DMV and they checked out the Cruiser put in the paperwork, and I was all set. I can tell you that I could have done that on another day and even though it has a Florida title they would tell me no way, I just got lucky that day and someone was lazy and let it go through, and at the state level the same thing must have happend. End result I have a perfectly legal Australian Troopy and since it has a California title I am 98% sure no other state would have a problem with it. And in case you are wondering it has all the original vin numbers from the firewall to the frame.
So people can quote rules or what they think they know all day long on Mud but at the end of the day, some how some way cruisers find a way to get titled and registered in the US. That being said my best advice would be to find what you are looking for here in the the US, pay the extra money they are asking for it and save yourself all the trouble and call it a day.
Cheers,
Michael