A PDP-10 port of GCC is nearly ready:
        http://pdp10.nocrew.org/gcc/
and there is an excellent PDP-10 emulator:
        http://klh10.trailing-edge.com/

The first version of the PDP-10 architecture, with an 18-bit address
space, would not be suitable for a port.  However, the later extended
architecture has a 30-bit address space.

-- 
Lars Brinkhoff          http://lars.nocrew.org/     Linux, GCC, PDP-10,
Brinkhoff Consulting    http://www.brinkhoff.se/    HTTP programming