Yes, there's Unicomp, and there's Ellipse's new production F62 and F77 boards, either with painstakingly recreated original Zinc cases, or modern aluminum ones.
If you want the closest modern thing to buckling spring from a modern switch, the closest I have felt are the Kailh box clickies with the thinnest click bar, since capacitive buckling spring actually has a very subtle tactile event when you remove the pressure stacking of the buckling spring itself. Another glaring difference is that the tactile event on these switches is quite high vs even membrane buckling spring. Box whites and pale blues might be something to look at if you absolutely must have a LEGO/kit, or fully custom board. You lose the sound, and they're never going to feel exactly the same. SPRiT makes what they claim to be progressive weight springs. None of the ones I have tried seemed to start to build at all (noticeably) until after the tactile event had already passed.
Ellipse's boards are literally meant to be customized any way you like. Are they too far removed from your end goal to be modified how you would prefer?