The histogram on a digital camera nearly makes the original implementation of the zone system obsolete. As I understood the zone system, it put numbers on the following concept: you explored various parts of the image, particularly the highlights and shadows, to see what would happen if you tried to capture them both within the range of zones available on your film. Would the major items in the shot be too light or dark for your previsualized image, would you need to alter development etc, or would you need to sacrifice shadow detail or highlights, if there was too much range etc. (Not trivializing, just simplifying).
The available range in a single digital capture seems to be a matter of discussion and isn't simply stated, and has improved quite a bit as sensor and processor technologies have evolved. It's probably beyond slide film, however. Once you understand the histogram (together with bracketing/blending/HDR tools to extend the DR beyond a single capture) the need for the zone system per se goes away. It's kinda built into a histogram. In other words, the histogram IS the new zone system
I have a Sekonic for my 4x5 and when I got the 4x5, I religiously metered my shots as all the best books described (and the Sekonic graciously merged them into a single exposure recommendation which matched my own "placements") I also used my Canon digital SLR to take shots of the same scene - adjusting the exposure based on the histogram to expose slightly less than what would have blown the highlights ("Expose right" in digital terminology). Sheet after sheet I did this and there was rarely a difference of more than 1/2 stop and the trannies look great. It was frequently "meter for the highlights and let the shadows fall where they may" - the latter being determined by the subsequent scan quality. I will now only override the histogram if I know I want to sacrifice the highlights to get better shadow details (or vice versa)
If you can get you mind around the 2-dimensional distribution of tones in the image on the focusing screen and its transformation to a histogram of the same tones now ordered by luminance, you'll see that the histogram is simply the result of many millions of single pixel spot meter measurements, placed on a scale of the range available for capture - it's done all the work of gathering readings and placing them in zones (many 000's of them). Only under severe conditions will you need to get the spot meter out to determine which particular blown highlights are in which location in the image.
I still carry, but only rarely use, the Sekonic. I think you'll find a histogram helps you implement the original ideas behind the zone system, only with more precision