All 60 of the 2011 are all RHD.
As for the 1960s Plus 4 SS, both RHD and LHD variants were produced; however, the problem will be proving originality. My understanding, which may be incorrect, is that there are a few tweaked Plus 4s running around which have had SS parts added.
Here is an older ad for a LHD Plus 4 SS
http://www.carandclassic.co.uk/car/C114152 
