Hello Pete. Congratulations on your inspired idea for the holiday of a lifetime. Every encouragement to actually do it. Please post photos.
However I think there is an important idea that this thread has not covered, so here goes.
1) The general wisdom I have always followed buying used cars is to buy the best I can afford, choose a good one, then, having bought it, assume its not half as well sorted as it seemed (Note I have never bought from Dicky who is a rare exception to this guidance) and drive it locally for the first 2,000 miles while I get to know it, find and fix its shortcomings.
2) For buying a used Maserati, as above plus: Get a pre purchase inspection by a recognised specialist in used Maseratis and have a £5k trouble fund in the bank at all times.
Now on the face of it, this doesn't fit well with your holiday of a lifetime. No one on this forum will want you to have the nightmare of a lifetime with a broken down car half way round the world from where you live. But I think we are all clear that the best possible way to do this journey is in a well sorted Maserati (you've already got the idea that it could be a soft top, hard top, GT or Quattroporte). The driving experience, the look of the car and the interior are all second to none and the car will naturally fit in its natural habitat.
So, all you guys I come to for advice (there are plenty of knowledgeable and sensible owners on this forum, Pete) what do you say?