I got my oil pump from the machinists I use, they are the same ones they use on the engines they build, but each pump comes apart upon delivery and is checked, up to 50% are rejected as not good enough.
They build engines, all sorts of engines got a genuine GT40 lump in at the mo for ground up rebuild, then run on one of their engine dynos.
If you want me to get you one just pm me, as they don't do posting out, too busy, mentally busy.
tabetha