I'll echo Karl's comments.
Seems the instrument mounting "face-plate" could be attached to the binnacle from it's back-side (inside the binnacle), so those attachments do not show on the outside (face). Then the binnacle itself could attach through the dash top and be accessed from below, also making those attachments not visible. Not only would this make future access easier, and trimming (covering) the surfaces easier, but it would also look cleaner without any hardware showing.
As I stated previously I'm not particularly fond of the X's dash. But I'll agree with you guys, the early style HVAC controls are cool. Even some of the instruments and switches are o.k., depending on the year. It's really more the overall shape/style of the dash in general I don't care for. In my opinion the later dash would have been better with some rounder contours, especially things like the binnacle. Straight, flat, squared-off lines can work to some extent in certain areas, but its just too much here. Makes it look like a rushed cardboard-box mock-up that was left unfinished. As if a young child made it for a school science project that they really weren't interested in doing but had to do. One example to illustrate what I mean, the radio box on the early dash...come on, even J.C. Whitney offered better styles of universal radio add-on panels.
If I ever get around to modifying my late model dash I might try some simple changes, like using a contoured instrument binnacle (perhaps the previously suggested Alfa Spider item) on the existing dash base. With a couple of other small changes to go along with that...to "soften" the overall contours more...and better covering materials (I love the stitched edges used on Ferrari's and other Euro models) it might be enough, rather than a full redesign of the entire dash from scratch. However what you are doing is definitely better, kudos. I have to admit when I first saw the beginning of this thread I wasn't sure it would work, but you are proving otherwise.
By the way, I did not even notice the instruments in Clark's original dash. Clark, do you have a better picture of them? I'd be interested in knowing if that is something from the factory or custom.
Karl, I'm curious if your comments about things like the steering wheel obstructing the view of the gauges, etc is in reference to the 308 dash or the X dash or both? P.S., sorry to hear of the misfortunes at home, hope the wife and kitchen are doing better. I was wondering why we had not seen you here as much lately.