I have driven RHD and LHD in france and here. I think LHD works well, your right hand does the complex thing of operating the gear stick. Overtaking in an R4 is an unrealistic ambition. So anything to do with that is not worth worrying about because its not going to happen. For me LHD is not a problem, except for walking to the wrong side of the car in the morning.
As somebody said above, getting one from a hot clime where they dont use salt is a good option. Then you can cosmetically improve it, but the core structure is sound. Thats what i have done for both my cars. Portugal seems to have lots, as does Spain, France and Italy. Leboncoin in France is good place to find them. Importing them is not difficult and there are folk about who know everything about making a successful importation. Just make sure you get the Registration/Carte Gris in the documents when you buy the car, in useable condition and preferably a pre 1983 for road tax reasons here. I have an 850 car with drum brakes, and I love it. It will drive all day at 65. I have driven it back here and back again to France with no problems except coping with all the fun.
