Depends on what your after. Later cars, are 1303’s which are not everyones cup of tea, me in particular, but obviously drive better. Best value for money is probably a late 60s one, but if you want an investment, the earlier the better. As for LHD issue. Obviously a conversion its an involved job. If someone has converted one I would be very careful, as the quality of the job can vary significantly, however, if the car was a dry state car, then it is likely to have less rust, although check the floorpans carefully, as even US cars rot here, due to being left overnight with the roof down. I would say ignoring LHD and RHD issue best to just go for the best car most rust free car you can find as they are harder to restore and cost more.