There were three iterations (that I recall) of the interface on color Macs - the first one had window controls that were black and white, the second had a subtle 3d effect, and the third (which I think you mean by "Platinum") had more depth and was mostly gray.
I personally preferred the second. Attempts at imitating grayish metal on screen don't appeal to me, and I thought OS X got even worse when they switched to the brushed metal look.
But I really liked the design theme for the physical cases that was also called "Platinum" even though I think it's generally considered an uninspired period for Apple. And I have nothing against the aluminium or titanium Mac cases either.
The one change I would make to a "neo-Mac" window manager would be to have handles on all sides of a window for resizing. Although I like the Mac approach of having scrollbars and a lower right resize control that are substantial and obvious, I also like the ability to resize from all sides like most other interfaces have. I know there were Mac programs for the classic OS that did implement something like that, but it was never universal.
https://github.com/timnetworks/Platinum9
I find this theme quite pleasing to use whenever I'm using a Linux desktop. However, it's not yet pixel-perfect, and this also doesn't address the fact that GTK and GNOME applications are written under a completely different set of UI guidelines than classic Mac apps were, and so it's still largely a Mac OS 8-like veneer over the Linux desktop.
Even so, this theme looks like an excellent foundation for a suite of GTK applications that employ the mid-1990s Apple Human Interface Guidelines. What would be tantalizing would be forks of AbiWord and GIMP that look and feel like Microsoft Word 5.1 and classic versions of Photoshop, respectively.