The mirror shown on Hendriks 59 356A is a "Durant" mirror and was originally fitted to 356C cars and then early 911. I also in the late 60's had no mirrors fitted to my 59 A. I bought a "Durant" in favour to the original "Aero" style because I prefered the style.
It took me along time to get the position correct on the door before drilling and all mirrors except for the racing style spyder one look best on the door not the wing.
41 years on and my original upholstered backs to my front seats have sunk somewhat so that now I have to raise myself in the seat to get a good view out of the mirror
I think the "Aero" probably gives you more of a chance to get the correct rear view. The Durant mirrors or copies of? are still available.
By the way, the Aero fitted A and B cars ( upto T5) the B T6 had Ponto Stabil mirrors.
Roy