So! You want to use Multics? (1979) [pdf]
bitsavers.org
bitsavers.org
Also: PL/I may not have been beautiful, but at least it had a safe memory model!
https://multics-wiki.swenson.org/index.php/Main_Page
There are also several public access Multics systems up and running.
It would be fun to have an FPGA implementation of the hardware, and/or a port of the system to modern (or relatively modern) processors that are generally available (perhaps some x86 processors that support segmentation.)
The X86 segmentation facility resembles Multics segments in name only.