From previous posts written, if there are holes in the left door skin, these would be in the correct position for the driver of a LHD drive car, but in the wrong position for the driver of a RHD car, the mirror will be too far forward to be of much use. This only applies to the early mirrors, due to the shape of the neck
The best thing is to adjust your seat for your normal driving position, get someone to hold the mirror in the optimum position on the passenger door and mark the position
I don't have a passenger door mirror on my RHD car, and it can be awkward when pulling out from the right hand kerb, especially with the soft top up, with less visibility, but for normal driving i get on OK. It would be far worse in a LHD car in the UK without a passenger mirror, almost impossible to drive safely
Have a look on here, and also look at the other link within the post, gives you dimensions of the holes for both a 230 and 280
https://www.sl113.org/forums/index.php?topic=36256.msg264930#msg264930