Hi Tom welcome to AO.
The 2.0 V6 TB was not a UK issue car, there are a few about in the UK but the vast majority of them are LHD, that said with a donor car and a bit of mechanical knowledge it wouldn't be hard to convert to RHD, whichever TB you looked at expect to be paying a bit more for insurance as well.
Having had both a 2.0 GTV and Spider i can testify they are great cars, they are gifted with user friendly handling and whilst they are a bit of the weighty side they are not that slow.
The 3.0 does have an engine note to die for, with the right exhaust note on it it is almost Ferrari sounding, price wise there is about a £1000 premium for a V6 over a twinnie, when driven normally there are reports that fuel consumption is not that different either.
Given the age of car you are looking at i would say leather is going to be a standard feature, as will air con etc, you may even be looking at one that drops its windows when the doors are open as well.
Service history is everything here....and not just nice stamps in a book, receipts that support that work being done as well,try and get a car that has had its belts and variator changed recently, that will mean you will not get hit with that big bill for a while to come yet.
if you have any more queries, fire away