You did well to convert to B&W, to judge from the colors in my old Kodachromes.
Actually, my Kodachromes are still pretty good; I was taught that the difference between stored Kodachrome and Ektachrome was this: Kodachrome lasts for ever if you keep it in the dark; Ektachrome fades quickly by ityself, in the dark or otherwise, but resists projection longer.
My greatest fear with 6x6 Ektachromes arose after a shoot for a knitwear company. For some reason, the client decided that looking at slides on a lightbox wasn't good enough, and he wanted to see them projected. So I had to hire a projector and sweat blood as he kept the things in the slot for what felt like minute after minute... I think one or two actually developed permananet buckles before he stopped lingering. Folks have no idea, and even worse, some won't listen.
Oddly enough, I kept very little 6x6 Ektachrome from those days, but truth to tell, the few that I have appear to me to look no worse than the 135 format Kodachromes. I never got to shoot 120 format Kodachrome. It must have looked beautiful.
