For what it’s worth, I had a similar experience with a Nikon 9000 ED and, earlier, a Dimage 5400, Vuescan and Silverfast. There is a “Kodachrome” setting in the drop down menu, but, unfortunately, the only way to scan Kodachrome to get it to look like Kodachrome is to calibrate your scanner with a Kodachrome calibration slide. Otherwise, as you have seen, it won’t look that different from Ektachrome.
https://www.silverfast.com/show/kodachrome-targets/en.html
Even more unfortunately, those it8 calibration slides are no longer available from anyone because they can’t be made without the K14process. When originally available they were $50, now the existing ones can be very expensive, if you can even find one. Made a world of difference once I calibrated my scanner with one.
Upon researching links I could post here which might explain that, I found one which indicated that you might already be aware of those targets.
https://www.lightroomqueen.com/comm...t-8-target-for-kodachrome-will-pay-150.41163/ So, I won’t go too deeply into the need, as you already are aware. The only thing I can offer is my opinion, from experience, that once the scanner is calibrated with the Kodachrome it8 target, Kodachrome scans won’t look like Ektachrome scans, they’ll look like Kodachrome.
(Most of the Kodachrome pix I see posted on the internet don’t look like Kodachrome for, I’m guessing, the fact they were scanned on scanners not calibrated for Kodachrome.)
Much you will find on the web is like this thread
https://www.dpreview.com/forums/thread/4397090 Where, none or almost none, of the respondents have any experience with a calibrated scanner, but don’t hesitate to offer advice on scanning Kodachrome, regardless.
It’s certainly possible to end up with a final file that looks like Kodachrome if you have the slide to be duped in front of you, but it takes work adjusting colors both while scanning and during post processing. Having an it8 calibration target slide for Kodachrome eliminates most of that.
Having said all that, since the target slides are NLA, this might be a situation where DSLR duplicating might give you a more accurate result since you wouldn’t be scanning with a scanner setup for “normal” transparencies.
You probably already know most or all of this. The only thing I might possibly have added is that a scanner calibrated for Kodachrome with a target slide will give you Kodachrome scans that don’t look like Ektachrome scans, very much at all, provided the Kodachrome you are scanning is in good condition. From personal experience.